WM9712L

AC'97 Audio and Touchpanel CODEC

WOLFSON MICROELECTRONICS plc

www.wolfsonmicro.com

Production Data, December 2003, Rev 4.0

2003 Wolfson Microelectronics plc.

DESCRIPTION

The WM9712L is a highly integrated input / output device
designed for mobile computing and communications. The
device can connect directly to a 4-wire or 5-wire touchpanel,
mono or stereo microphones, stereo headphones and a
mono speaker, reducing total component count in the
system. Additionally, phone input and output pins are
provided

for

seamless

integration

with

wireless

communication devices.

The WM9712L also offers up to four auxiliary ADC inputs
for analogue measurements such as temperature or light,
and five GPIO pins for interfacing to buttons or other digital
devices. To monitor the battery voltage in portable systems,
the WM9712L has two uncommitted comparator inputs.

All device functions are accessed and controlled through a
single AC-Link interface compliant with the AC'97 standard.
Additionally, the WM9712L can generate interrupts to
indicate pen down, pen up, availability of touchpanel data,
low battery, dead battery, and GPIO conditions.

The WM9712L operates at supply voltages from 1.8 to 3.6
Volts. Each section of the chip can be powered down under
software control to save power. The device is available in a
small leadless 7x7mm QFN package, ideal for use in hand-
held portable systems, or in the industry standard 48-pin
TQFP package.

FEATURES

AC'97 Rev 2.2 compatible stereo codec

- DAC SNR 94dB, THD 87dB
- ADC SNR 92dB, THD 87dB
- Variable Rate Audio, supports all WinCE sample rates
- Tone Control, Bass Boost and 3D Enhancement

On-chip 45mW headphone driver

On-chip 400mW mono speaker driver

Stereo, mono or differential microphone input

- Automatic Level Control (ALC)

Auxiliary mono DAC (ring tone or DC level generation)

Seamless interface to wireless chipset

Resistive touchpanel interface

- Supports 4-wire and 5-wire panels
- 12-bit resolution, INL

2 LSBs (<0.5 pixels)

- X, Y and touch-pressure (Z) measurement
- Pen-down detection supported in Sleep Mode

Up to 5 GPIO pins

2 comparator inputs for battery monitoring

Up to 4 auxiliary ADC inputs

1.8V to 3.6V supplies

7x7mm QFN or 48-pin TQFP package options

APPLICATIONS

Personal Digital Assistants (PDA)

Smartphones

Handheld and Tablet Computers

BLOCK DIAGRAM

WM9712L

Production Data

PD Rev 4.0 December 2003

TABLE OF CONTENTS

DESCRIPTION .......................................................................................................1
FEATURES.............................................................................................................1
APPLICATIONS .....................................................................................................1
BLOCK DIAGRAM .................................................................................................1
TABLE OF CONTENTS .........................................................................................2
PIN CONFIGURATION...........................................................................................4
ORDERING INFORMATION ..................................................................................4
PIN DESCRIPTION ................................................................................................5
ABSOLUTE MAXIMUM RATINGS .........................................................................6
RECOMMENDED OPERATING CONDITIONS .....................................................6
ELECTRICAL CHARACTERISTICS ......................................................................7

AUDIO OUTPUTS.......................................................................................................... 7

AUDIO INPUTS.............................................................................................................. 8

AUXILIARY MONO DAC (AUXDAC).............................................................................. 8

TOUCHPANEL AND AUXILIARY ADC .......................................................................... 9

COMPARATORS ........................................................................................................... 9

REFERENCE VOLTAGES ........................................................................................... 10

DIGITAL INTERFACE CHARACTERISTICS................................................................ 10

HEADPHONE / SPEAKER OUTPUT THD VERSUS POWER ..................................... 11

POWER CONSUMPTION............................................................................................ 12

DEVICE DESCRIPTION .......................................................................................13

INTRODUCTION.......................................................................................................... 13

AUDIO PATHS OVERVIEW......................................................................................... 14

AUDIO INPUTS ....................................................................................................15

LINE INPUT ................................................................................................................. 15

MICROPHONE INPUT................................................................................................. 15

PHONE INPUT............................................................................................................. 17

PCBEEP INPUT ........................................................................................................... 18

AUDIO ADC..........................................................................................................19

RECORD SELECTOR ................................................................................................. 20

RECORD GAIN............................................................................................................ 21

AUTOMATIC LEVEL CONTROL.................................................................................. 22

AUDIO DACS .......................................................................................................25

STEREO DAC.............................................................................................................. 25

AUXILIARY DAC.......................................................................................................... 28

ANALOGUE AUDIO OUTPUTS ...........................................................................29

HEADPHONE OUTPUTS HPOUTL AND HPOUTR.................................................. 29

EAR SPEAKER OUTPUT OUT3............................................................................... 30

LOUDSPEAKER OUTPUTS LOUT2 AND ROUT2.................................................... 31

PHONE OUTPUT (MONOOUT)................................................................................... 32

THERMAL SENSOR .................................................................................................... 32

JACK INSERTION AND AUTO-SWITCHING............................................................... 33

DIGITAL AUDIO (SPDIF) OUTPUT ............................................................................. 34

AUDIO MIXERS ........................................................................................................... 35

Production Data

WM9712L

PD Rev 4.0 December 2003

VARIABLE RATE AUDIO / SAMPLE RATE CONVERSION ...............................37
TOUCHPANEL INTERFACE................................................................................38

PRINCIPLE OF OPERATION - FOUR-WIRE TOUCHPANEL ..................................... 38

PRINCIPLE OF OPERATION - FIVE-WIRE TOUCHPANEL........................................ 40

CONTROLLING THE TOUCHPANEL DIGITISER ....................................................... 42

AUXILIARY ADC INPUTS ....................................................................................47

BATTERY MEASUREMENT USING THE BMON/AUX3 PIN ....................................... 47

BATTERY ALARM AND ANALOGUE COMPARATORS ....................................48
GPIO AND INTERRUPT CONTROL ....................................................................51
AC97 DATA AND CONTROL INTERFACE .........................................................58

INTERFACE PROTOCOL............................................................................................ 58

INTERFACE TIMING ................................................................................................... 59

REGISTER MAP...................................................................................................62

APPLICATIONS INFORMATION .........................................................................71

RECOMMENDED EXTERNAL COMPONENTS........................................................... 71

LINE OUTPUT ............................................................................................................. 72

AC-COUPLED HEADPHONE OUTPUT....................................................................... 73

DC COUPLED (CAPLESS) HEADPHONE OUTPUT ................................................... 73

BTL LOUDSPEAKER OUTPUT ................................................................................... 74

COMBINED HEADSET / BTL EAR SPEAKER............................................................. 74

COMBINED HEADSET / SINGLE-ENDED EAR SPEAKER......................................... 74

JACK INSERT DETECTION ........................................................................................ 75

HOOKSWITCH DETECTION....................................................................................... 75

PACKAGE DRAWING - QFN ...............................................................................76
PACKAGE DRAWING TQFP ............................................................................77
IMPORTANT NOTICE ..........................................................................................78

ADDRESS:................................................................................................................... 78

Production Data

WM9712L

PD Rev 4.0 December 2003

PIN DESCRIPTION

PIN

NAME

TYPE

DESCRIPTION

DBVDD

Supply

Digital I/O Buffer Supply

XTLIN

Digital Input

Clock Crystal Connection 1 / External Clock Input

XTLOUT

Digital Output

Clock Crystal Connection 2

DGND1

Supply

Digital Ground (return path for both DCVDD and DBVDD)

SDATAOUT

Digital Input

Serial Data Output from Controller / Input to WM9712L

BITCLK

Digital Output

Serial Interface Clock Output to Controller

DGND2

Supply

Digital Ground (return path for both DCVDD and DBVDD)

SDATAIN

Digital Output

Serial Data Input to Controller / Output from WM9712L

DCVDD

Supply

Digital Core Supply

SYNC

Digital Input

Serial Interface Synchronisation Pulse from Controller

RESETB

Digital Input

Reset (asynchronous, active Low, resets all registers to their default)

WIPER / AUX4

Analogue Input

Top Sheet Connection for 5-wire Touchpanels / Auxiliary ADC Input

TPVDD

Supply

Touchpanel Driver Supply

X+/BR

Analogue Input

Touchpanel Connection: X+ (Right) for 4-wire / bottom right for 5-wire

Y+/TR

Analogue Input

Touchpanel Connection: Y+ (Top) for 4-wire / top right for 5-wire

X-/TL

Analogue Input

Touchpanel Connection: X- (Left) for 4-wire / top left for 5-wire

Y-/BL

Analogue Input

Touchpanel Connection: Y- (Bottom) for 4-wire / bottom left for 5-wire

TPGND

Supply

Touchpanel Driver Ground

PCBEEP

Analogue Input

Line Input to analogue audio mixers, typically used for beeps

PHONE

Analogue Input

Phone Input (RX)

MIC1

Analogue Input

Left Microphone or Microphone 1 Input

MIC2

Analogue Input

Right Microphone or Microphone 2 Input

LINEINL

Analogue Input

Left Line Input

LINEINR

Analogue Input

Right Line Input

AVDD

Supply

Analogue Supply (feeds audio DACs, ADCs, PGAs, mic boost,
mixers)

AGND

Supply

Analogue Ground

VREF

Analogue Output

Internal Reference Voltage (buffered CAP2)

MICBIAS

Analogue Output

Bias Voltage for Microphones (buffered CAP2

1.8)

COMP1 / AUX1

Analogue Input

Comparator 1 (dead battery alarm) / Auxiliary ADC Input 1

COMP2 / AUX2

Analogue Input

Comparator 2 (low battery alarm) / Auxiliary ADC Input 2

BMON / AUX3

Analogue Input

Battery Monitor Input / Auxiliary ADC Input 3

CAP2

Analogue In / Out

Internal Reference Voltage (normally AVDD/2, if not overdriven)

MONOOUT

Analogue Output

Mono Output, intended for Phone TX signal

SPKGND

Supply

Speaker Ground (feeds output buffers on pins 35 and 36)

LOUT2

Analogue Output

Left Output 2 (Speaker, Line or Headphone)

ROUT2

Analogue Output

Right Output 2 (Speaker, Line or Headphone)

OUT3

Analogue Output

Analogue Output 3 (from AUXDAC or headphone pseudo-ground)

SPKVDD

Supply

Speaker Supply (feeds output buffers on pins 35 and 36)

HPOUTL

Analogue Output

Headphone Left Output

HPGND

Supply

Headphone Ground (feeds output buffers on pins 37, 39, 41)

HPOUTR

Analogue Output

Headphone Left Output

AGND2

Supply

Analogue Ground, Chip Substrate

HPVDD

Supply

Headphone Supply (feeds output buffers on pins 37, 39, 41)

GPIO1

Digital In / Out

GPIO Pin 1

GPIO2 / IRQ

Digital In / Out

GPIO Pin 2 or IRQ (Interrupt Request) Output

GPIO3 / PENDOWN

Digital In / Out

GPIO Pin 3 or Pen Down Output

GPIO4 / ADA / MASK

Digital In / Out

GPIO Pin 4 or ADA (ADC Data Available) Output or Mask input

GPIO5 / SPDIF_OUT

Digital In / Out

GPIO Pin 5 or SPDIF Digital Audio Output

WM9712L

Production Data

PD Rev 4.0 December 2003

ABSOLUTE MAXIMUM RATINGS

Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at
or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical
Characteristics at the test conditions specified.

ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible
to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage
of this device.

Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage
conditions prior to surface mount assembly. These levels are:

MSL1 = unlimited floor life at <30

C / 85% Relative Humidity. Not normally stored in moisture barrier bag.

MSL2 = out of bag storage for 1 year at <30

C / 60% Relative Humidity. Supplied in moisture barrier bag.

MSL3 = out of bag storage for 168 hours at <30

C / 60% Relative Humidity. Supplied in moisture barrier bag.

The Moisture Sensitivity Level for each package type is specified in Ordering Information.

Note:
The TQFP version is classified as MSL1 and does not require to be drybagged but will be supplied as such, labelled as MSL1.

CONDITION

MIN

MAX

Digital supply voltages (DCVDD, DBVDD)

-0.3V

+3.63V

Analogue supply voltages (AVDD, HPVDD, SPKVDD, TPVDD)

-0.3V

+3.63V

Touchpanel supply voltage (TPVDD)

AVDD -0.3V

AVDD +0.3V

Voltage range digital inputs

DGND

-0.3V

DBVDD +0.3V

Voltage range analogue inputs

AGND

-0.3V

AVDD +0.3V

Voltage range touchpanel Inputs X+, X-, Y+ and Y-

TPVDD +0.3V

Voltage range touchpanel Inputs X+, X-, Y+ and Y-

AVDD +0.3V

Voltage range, BMON/AUX3 (pin31)

+5V

Operating temperature range, T

-25

+85

Storage temperature (TQFP package only)

-65

+150

Lead temperature (soldering 10 seconds)

+240

Lead temperature (soldering 2 minutes)

+183

RECOMMENDED OPERATING CONDITIONS

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Digital input/output buffer
supply range

DBVDD

Notes 1, 2

1.8

3.3

3.6 or

AVDD+0.3

Digital core supply range

DCVDD

Notes 1, 2

1.8

3.3

3.6 or

AVDD+0.3

Analogue supply range

AVDD, HPVDD,

SPKVDD, TPVDD

1.8

3.3

3.6

Digital ground

DCGND, DBGND

Analogue ground

AGND, HPGND,

SPKGND, TPGND

Difference AGND to DGND

Note 3

-0.3

+0.3

Notes:

AVDD, DCVDD and DBVDD can all be different

Digital supplies (DCVDD, DBVDD) must not exceed analogue supplies (AVDD, HPVDD, SPKVDD, TPVDD) by more
than 0.3V

AGND is normally the same as DGND

Production Data

WM9712L

PD Rev 4.0 December 2003

ELECTRICAL CHARACTERISTICS

AUDIO OUTPUTS

Test Conditions
DBVDD=3.3V, DCVDD = 3.3V, AVDD=HPVDD=SPKVDD =3.3V, T

= +25

C, 1kHz signal, fs = 48kHz, 18-bit audio data unless

otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

DAC to Line-Out (HPOUTL/R or MONOOUT with 10k

/ 50pF load)

Full-scale output

AVDD = 3.3V, PGA gains

set to 0dB

V rms

Signal to Noise Ratio

(A-weighted)

SNR

Total Harmonic Distortion

THD

-3dB output

-87

-80

Power Supply Rejection

PSRR

100mV, 20Hz to 20kHz

signal on AVDD

Speaker Output (LOUT2/ROUT2 with 8

bridge tied load, INV=1)

Output Power

Output power is very closely correlated with THD; see below.

=200mW

-67

0.045

Total Harmonic Distortion

THD

=400mW

-66

0.050

-60

Signal to Noise Ratio

(A-weighted)

SNR

100

Headphone Output (HPOUTL/R, OUT3 or LOUT2/ROUT2 with 16

or 32

load)

Output Power per channel

Output power is very closely correlated with THD; see below.

=10mW, R

=16

-80

=10mW, R

=32

-80

=20mW, R

=16

-79

-70

Total Harmonic Distortion

THD

=20mW, R

=32

-79

Signal to Noise Ratio

(A-weighted)

SNR

Note:

All THD values are valid for the output power level quoted above for example, at HPVDD=3.3V and R

=16

, THD is

80dB when output power is 10mW. Higher output power is possible, but will result in a deterioration in THD.

WM9712L

Production Data

PD Rev 4.0 December 2003

AUDIO INPUTS

Test Conditions

DBVDD=3.3V, DCVDD = 3.3V, AVDD = 3.3V, T

= +25

C, 1kHz signal, fs = 48kHz, 18-bit audio data unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

LINEINL/R, MICL/R and PHONE pins

AVDD = 3.3V

1.0

AVDD = 1.8V

0.545

Full Scale Input Signal Level

(for ADC 0dB Input at 0dB Gain)

INFS

differential input mode

(MS = 01)

half of the value listed above

V rms

0dB PGA gain

Input Resistance

12dB PGA gain

Input Capacitance

Line input to ADC (LINEINL, LINEINR, PHONE)

Signal to Noise Ratio

(A-weighted)

SNR

Total Harmonic Distortion

THD

-6dBFs

-87

-80

Power Supply Rejection

PSRR

20Hz to 20kHz

Microphone input to ADC (MIC1/2 pins)

Signal to Noise Ratio

(A-weighted)

SNR

20dB boost enabled

Total Harmonic Distortion

THD

20dB boost enabled

-80

Power Supply Rejection Ratio

PSRR

Common Mode Rejection Ratio

CMRR

Differential mic mode

TBD

AUXILIARY MONO DAC (AUXDAC)

Test Conditions
AVDD = 3.3V, T

= +25

C, unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Resolution

bits

Full scale output voltage

AVDD=3.3V

Vrms

Signal to Noise Ratio

(A-weighted)

SNR

Total Harmonic Distortion

THD

-62

-50

Production Data

WM9712L

PD Rev 4.0 December 2003

TOUCHPANEL AND AUXILIARY ADC

Test Conditions

DBVDD=3.3V, DCVDD = 3.3V, AVDD = TPVDD = 3.3V, T

= +25

C, MCLK = 24.576 MHz, unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Input Pins X+, X-, Y+, Y-, WIPER/AUX4, COMP1/AUX1, COMP2/AUX2 and BMON/AUX3

Input Voltage

AGND

AVDD

Input leakage current

AUX pin not selected as

AUX ADC input

<10

ADC Resolution

bits

Differential Non-Linearity Error

DNL

0.25

LSB

Integral Non-Linearity Error

INL

LSB

Offset Error

LSB

Gain Error

LSB

Power Supply Rejection

PSRR

Throughput Rate

DEL = 1111

(zero settling time)

kHz

Settling Time (programmable)

MCLK = 24.576MHz

Conversion Time

Note: touch pressure

measurements require

two conversions

20.8

Switch matrix resistance

Programmable Pull-up resistor

RPU = 000001

Pen down detector threshold

VDD/2

PIL = 1

400

Pressure measurement current

PIL = 0

200

BMON/AUX3 (pin 31 only)

AVDD = 3.3V

AGND

Input Range

AVDD = 1.8V

AGND

3.3

Scaling

-3%

1/3

+3%

during measurement

Input Resistance (Note 1)

average over time

30 /

duty cycle

Note:

1. Current only flows into pin 31 during a measurement. At all other times, BMON/AUX3 is effectively an open circuit.

COMPARATORS

Test Conditions

AVDD = 3.3V, T

= +25

C, unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

COMP1/AUX1 and COMP2/AUX2 (pins 29, 30)

Input Voltage

AGND

AVDD

Input leakage current

pin not selected as AUX

ADC input

<10

Comparator Input Offset

(COMP1, COMP2 only)

-50

+50

COMP2 delay (COMP2 only)

24.576MHz crystal

10.9

WM9712L

Production Data

PD Rev 4.0 December 2003

REFERENCE VOLTAGES

Test Conditions

DBVDD=3.3V, DCVDD = 3.3V, AVDD = 3.3V, T

= +25

C, 1kHz signal, fs = 48kHz, 18-bit audio data unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Audio ADCs, DACs, Mixers

Reference Input/Output

CAP2 pin

1.6

1.65

1.7

Buffered Reference Output

VREF pin

1.6

1.65

1.7

Microphone Bias

Bias Voltage

MICBIAS

2.88

2.97

3.06

Bias Current Source

MICBIAS

Output Noise Voltage

1K to 20kHz

nV/

DIGITAL INTERFACE CHARACTERISTICS

Test Conditions

DBVDD = 3.3V, DCVDD = 3.3V, T

= +25

C, unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Digital Logic Levels (all digital input or output pins) CMOS Levels

Input HIGH level

DBVDD

0.7

Input LOW level

DBVDD

0.3

Output HIGH level

source current = 2mA

DBVDD

0.9

Output LOW level

sink current = 2mA

DBVDD

0.1

Clock Frequency

Master clock (XTLIN pin)

24.576

MHz

AC'97 bit clock (BIT_CLK pin)

12.288

MHz

AC'97 sync pulse (SYNC pin)

kHz

Note:

All audio and non-audio sample rates and other timing scales proportionately with the master clock.

For signal timing on the AC-Link, please refer to the AC'97 specification (Revision 2.2)

WM9712L

Production Data

PD Rev 4.0 December 2003

POWER CONSUMPTION

The power consumption of the WM9712L depends on the following factors.

Supply voltages: Reducing the supply voltages also reduces digital supply currents, and therefore results in significant
power savings especially in the digital sections of the WM9712L.

Operating mode: Significant power savings can be achieved by always disabling parts of the WM9712L that are not
used (e.g. audio ADC, DAC, touchpanel digitiser).

Mode Description

26h 14:8

24h 15:0

Other Settings

Total Power

I (mA)

(mW)

OFF (lowest possible power)

1111111 0111111111111111 58h, SVD = 1

3.3

0.0005

3.3

0.00165

Clocks stopped

2.5

0.0004

2.5

0.001

1.8

0.0003

1.8

0.00054

LPS (Low Power Standby)

1111111 0111111111111111

3.3

0.005

3.3

0.0165

VREF maintained using 1MOhm string

2.5

0.004

2.5

0.01

1.8

0.003

1.8

0.0054

Standby Mode (ready to playback)

1110111 0111111111111111

3.3

0.56

3.3

1.848

VREF maintained using 50kOhm string

2.5

0.37

2.5

0.925

1.8

0.241

1.8

0.4338

"Idle" Mode

1100111 0111111111111111

3.3

1.1

3.3

3.63

VREF maintained using 50kOhm string

2.5

0.76

2.5

1.9

use LPS mode instead, if possible

1.8

0.508

1.8

0.9144

Touchpanel only (waiting for pen-down)

1101111 0111111111111111 76h = 0C00h

3.3

0.05

3.3

1.301

3.3

3.26

15.2163

AC-Link running

78h = 0001h

2.5

0.02

2.5

0.883

2.5

2.1

7.5075

1.8

0.009

1.8

0.571

1.8

1.41

3.582

Touchpanel only (continuous conversion)

1001111 0111111111111111 76h = 0C00h

3.3

0.08

3.3

5.85

3.3

2.67

28.38

93.75 points per second

78h = C001h

2.5

0.04

2.5

3.922

2.5

2.1

15.155

1.8

0.027

1.8

2.87

1.8

1.41

7.7526

Phone Call - using headphone / ear speaker

0110011 0111100010101100 0Eh, bit 7 = 1

3.3

2.36

3.3

7.788

HPOUTL, HPOUTR and OUT3 active

(mic gain boost)

2.5

1.838

2.5

4.595

AC-Link stopped

1.8

1.218

1.8

2.1924

Phone Call - using loudspeaker

1110011 0111101100110100 0Eh, bit 7 = 1

3.3

2.385

3.3

7.8705

AC-Link stopped

(mic gain boost)

2.5

1.837

2.5

4.5925

1.8

1.218

1.8

2.1924

Record from mono microphone

1000110 0110101111111111 0Eh, bit 7 = 1

3.3

3.27

3.3

11.21

3.3

2.6

56.364

with MICBIAS

(mic gain boost)

2.5

2.66

2.5

7.78

2.5

2.13

31.425

all analogue outputs disabled

1.8

1.838

1.8

5.21

1.8

1.41

15.2244

Record phone call

0000000 0000000010001000 0Eh, bit 7 = 1

3.3

9.461

3.3

12.22

3.3

2.62

80.1933

both sides mixed to mono

(mic gain boost)

2.5

7.46

2.5

8.552

2.5

2.1

45.28

call using headphone / ear speaker

1.8

5.318

1.8

5.799

1.8

1.48

22.6746

DAC Playback - using loudspeaker

1000001 0001111101110111

3.3

3.45

3.3

9.884

3.3

2.6

52.5822

2.5

2.549

2.5

6.755

2.5

2.1

28.51

1.8

1.738

1.8

4.606

1.8

1.41

13.9572

DAC Playback - using headphone

0000001 0001110011101111

3.3

3.62

3.3

9.8

3.3

2.6

52.866

2.5

2.71

2.5

6.78

2.5

2.1

28.975

1.8

1.748

1.8

4.606

1.8

1.47

14.0832

DAC Playback - to Line-out

0000001 0001110011110111

3.3

3.62

3.3

9.8

3.3

2.6

52.866

2.5

2.71

2.5

6.78

2.5

2.1

28.975

1.8

1.748

1.8

4.606

1.8

1.41

13.9752

Maximum Power (everything on)

0000000 0000000000000000 0Eh, bit 7 = 1

3.3

9.593

3.3

12.26

3.3

2.62

80.7609

(mic gain boost)

2.5

7.37

2.5

8.563

2.5

2.12

45.1325

1.8

5.388

1.8

5.8

1.8

1.48

22.8024

AVDD

DCVDD

DBVDD

Table 1 Supply Current Consumption

Notes:

All figures are at T

= +25

C, audio sample rate fs = 48kHz, with zero signal (quiescent).

The power dissipated in the headphone, speaker and touchpanel is not included in the above table.

Production Data

WM9712L

PD Rev 4.0 December 2003

DEVICE DESCRIPTION

INTRODUCTION

The WM9712L is designed to meet the mixed-signal requirements of portable and wireless computer

systems. It includes audio recording and playback, touchpanel digitisation, battery monitoring,

auxiliary ADC and GPIO functions, all controlled through a single 5-wire AC-Link interface.

SOFTWARE SUPPORT

The basic audio features of the WM9712L are software compatible with standard AC'97 device

drivers. However, to better support the touchpanel and other additional functions, Wolfson

Microelectronics supplies custom device drivers for selected CPUs and operating systems. Please

contact your local Wolfson Sales Office for more information.

AC'97 COMPATIBILITY

The WM9712L uses an AC'97 interface to communicate with a microprocessor or controller. The

audio and GPIO functions are largely compliant with AC'97 Revision 2.2. The following differences

from the AC'97 standard are noted:

Pinout: The function of some pins has been changed to support device specific features.
The PHONE and PCBEEP pins have been moved to different locations on the device
package.

Package: The default package for the WM9712L is a 7

7mm leadless QFN package.

However, it may also be supplied in a 48-pin TQFP package, as specified in the AC'97
standard.

Audio mixing: The WM9712L handles all the audio functions of a smartphone, including
audio playback, voice recording, phone calls, phone call recording, ring tones, as well as
simultaneous use of these features. The AC'97 mixer architecture does not fully support
this. The WM9712L therefore uses a modified AC'97 mixer architecture with three
separate mixers.

Tone Control, Bass Boost and 3D Enhancement: These functions are implemented in
the digital domain and therefore affect only signals being played through the audio
DACs, not all output signals as stipulated in AC'97.

Some other functions are additional to AC'97:

On-chip BTL loudspeaker driver

On-chip BTL driver for ear speaker (phone receiver)

Auxiliary mono DAC for ring tones, system alerts etc.

Touchpanel controller

Auxiliary ADC Inputs

2 Analogue Comparators for Battery Alarm

Programmable Filter Characteristics for Tone Control and 3D Enhancement

WM9712L

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PD Rev 4.0 December 2003

AUDIO PATHS OVERVIEW

LINEL PGA

LOUT2

Pin 35

MONOOUT

Pin 33

ROUT2

Pin 36

OUT3

Pin 37

LINER

MICR

DACR

LINER

MICR

DACR

PHONE

PCBEEP

MONOMIX

PHONE

PCBEEP

MONOMIX

MICL

ALCL

ALCR

ALCL

ALCR

Left Channel

18 Bit ADC

Variable Slot
5C:1-0 (ASS)

5C:3 (HPF)

5C:4 (ADCO)

ALC:5Ch/60h/62h

12 Bit Resistor

string DAC

2Eh/64h/12h:0(EN)

AUXDAC

SPKRMIX

FROM
LINEL

PGA

FROM

DACL

to SPKR MIXER

Left Channel

18 Bit DAC

18h:12-8

00000 = +12dB

11111 = -34.5dB

headphone

mixer L

h:1

0Ah:1

5-12

Phone

Mixer

h:1

0Ah7:4

-1

10h:12-8

00000 = +12dB

11111 = -34.5dB

0Ch:0-4

00000 = +12dB

11111 = -34.5dB

0Eh:12-8

00000 = +12dB

11111 = -34.5dB

1Ah:
10-8

1Ah:14

0 = 0dB

1 = 20dB

18h:4-0

00000 = +12dB

11111 = -34.5dB

10h:5-0

00000 = +12dB

11111 = -34.5dB

0Eh:5-0

00000 = +12dB

11111 = -34.5dB

headphone

mixer R

0Ah:1

5-12

Speaker

Mixer

h:1

0Ch:14

0Ah

:11-

Right Channel

18 Bit ADC

Variable Slot
5C:1-0 (ASS)

5C:3 (HPF)

5C:4 (ADCO)

1Ah:

2-0

Zero-
cross

detect

02h:12-8

00000 = 0dB

11111 = -46.5dB

Zero-
cross

detect

04h:12-8

00000 = 0dB

11111 = -46.5dB

HPOUTL

Pin 39

Zero-
cross

detect

06h:4-0

00000 = 0dB

11111 = -46.5dB

Zero-
cross

detect

16h:4-0

00000 = 0dB

11111 = -46.5dB

Zero-
cross

detect

04h:4-0

00000 = 0dB

11111 = -46.5dB

HPOUTR

Pin 41

Zero-
cross

detect

02h:4-0

00000 = 0dB

11111 = -46.5dB

0dB / 20dB

OEh:6-5 (MS)

ALC:5Ch/60h/62h

0Eh:6-5

(MS)

5Ch:8 (DS)

02h:6 (INV)

02h:7 (ZC)

02h:15 (MUTE)

04h:7 (ZC)

04h:15 (MUTE)

06h:7 (ZC)

06h:15 (MUTE)

16h:7 (ZC)

16h:15 (MUTE)

04h:7 (ZC)

04h:15 (MUTE)

02h:7 (ZC)

02h:15 (MUTE)

16h:10-9
(OUT3SRC)

16h:8 (SRC)

1Ah:14

0 = 0dB

1 = 20dB

1Ch:6 (GRR=1)
1Ch:5-0
11111 = +30dB
00000 = -17.25dB

1Ch:6 (GRR=0)
1Ch:3:0
0000 = 0db
1111 = +22.5dB

1Ch:6 (GRL=1)
1Ch:13-8
11111 = +30dB
00000 = -17.25dB

1Ch:13 (GRL=0)
1Ch:11:8
0000 = 0db
1111 = +22.5dB

Slot 3

Tone and 3D

08h / 22h /

20h:13 (3DE)

Slot 4

Tone and 3D

08h / 22h /

20h:13 (3DE)

AC Link

PCM
PGA

ADC
PGA

PHONE PGA

MICL PGA

LINER PGA

MICR PGA

Right Channel

18 Bit DAC

L Line Volume

R Line Volume

L Headphone Volume

R Headphone Volume

Mono Volume

OUT3 Volume

500k

50k

PR3 (REF disable) &

58h:10 (SVD)

3.6k

4.5k

h:1

6dB -> -15dB

18h:1

h:1

18h:1

h:1

14h:

15-1

h:13

14h:

15-1

h:1

1-7

h:11

-8

-7

-8

-1

h:11

-8

6dB -> -15dB

0dB / 20dB

6dB -> -15dB

0dB / 20dB

6dB -> -15dB

16h:8 (SRC)

1Ch:15 (Mute)

Gain Ranges:

1Ch:15 (Mute)

14h:15-12

0Eh

:14+

14h:15-12

ADC Left

20h:7

(Loopback)

AC Link

ADC Right

20h:7

(Loopback)

6dB -> -15dB

0dB / 20dB

MICBIAS

Pin 28

LINEINL

Pin 23

PCBEEP

Pin 19

PHONE

Pin 20

MIC1

Pin 21

LINEINR

Pin 24

MIC2

Pin 22

AVDD
Pin 25

VREF

Pin 27

AGND
Pin 24

CAP2

Pin 32

Figure 1 Audio Paths Overview

Production Data

WM9712L

PD Rev 4.0 December 2003

AUDIO INPUTS

The following sections give an overview of the analogue audio input pins and their function. For more

information on recommended external components, please refer to the "Applications Information"

section.

LINE INPUT

The LINEINL and LINEINR inputs are designed to record line level signals, and/or to mix into one of

the analogue outputs.

Both pins are directly connected to the record selector. The record PGA adjusts the recording

volume, controlled by register 1Ch or by the ALC function.

For analogue mixing, the line input signals pass through a separate PGA, controlled by register 10h.

The signals can be routed into all three output mixers (headphone, speaker and phone). Each

LINEIN-to-mixer path has an independent mute bit. When the line inputs are not used, the line-in

PGA can be switched off to save power (see "Power Management" section).

LINEINL and LINEINR are biased internally to the reference voltage VREF. Whenever the inputs are

muted or the device placed into standby mode, the inputs remain biased to VREF using special anti-

thump circuitry to suppress any audible clicks when changing inputs.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

12:8

LINEINL

VOL

01000

(0dB)

LINEINL input gain

00000: +12dB

... (1.5dB steps)

11111: -34.5dB

4:0

LINEINR

VOL

01000

(0dB)

LINEINR input gain

similar to LINEINLVOL

L2H

Mute LINEIN path to headphone mixer

1: Mute, 0: No mute (ON)

L2S

Mute LINEIN path to speaker mixer

1: Mute, 0: No mute (ON)

10h

L2P

Mute LINEIN path to phone mixer

1: Mute, 0: No mute (ON)

Table 2 Line Input Control

MICROPHONE INPUT

The MIC1 and MIC2 inputs are designed for direct connection to single-ended mono, stereo or

differential mono microphone. If the microphone is mono, the same signal appears on both left and

right channels. In stereo mode, MIC1 is routed to the left and MIC2 to the right channel.

For voice recording, the microphone signal is directly connected to the record selector. The record

PGA adjusts the recording volume, controlled by register 1Ch or by the ALC function.

For analogue mixing, the signal passes through a separate PGA, controlled by register 0Eh. The

microphone signal can be routed into the phone mixer (for normal phone call operation) and/or the

headphone mixer (using register 14h, see "Audio Mixers / Sidetone Control" section), but not into the

speaker mixer (to prevent acoustic feedback from the speaker into the microphone). When the

microphone inputs are not used, the microphone PGA can be switched off to save power (see

"Power Management" section).

MIC1 and MIC2 are biased internally to the reference voltage VREF. Whenever the inputs are muted

or the device placed into standby mode, the inputs remain biased to VREF using special anti-thump

circuitry to suppress any audible clicks when changing inputs.

WM9712L

Production Data

PD Rev 4.0 December 2003

It is also possible to use the LINEINL and LINEINR pins as a second differential microphone input.

This is achieved by setting the DS bit (register 5Ch, bit 11) to `1'. This disables the line-in audio paths

and routes the signal from LINEINL and LINEINR through the differential mic path, as if it came from

the MIC1 and MIC2 pins. Only one differential microphone be used at a time. The DS bit only has an

effect when MS = 01 (differential mode).

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

M12P

Mute MIC1 path to phone mixer

1: Mute, 0: No mute (ON)

M22P

Mute MIC2 path to phone mixer

1: Mute, 0: No mute (ON)

12:8

LMICVOL

01000

(0dB)

Left microphone volume

Only used when MS = 11

Similar to MICVOL

20dB

Microphone gain boost (Note 1)

1: 20dB boost ON

0: No boost (0dB gain)

Microphone mode select

Single-ended mono (left)

left = right = MIC1 (pin 21)

Volume controlled by MICVOL

Differential mono mode

left = right = MIC1 MIC2

Volume controlled by MICVOL

Single-ended mono (right)

left = right = MIC2 (pin 22)

Volume controlled by MICVOL

6:5

Stereo mode

MIC1 = left, MIC2 = right

Left Volume controlled by LMICVOL

Right volume controlled by MICVOL

0Eh

Mic Volume

4:0

MICVOL

01000

(0dB)

Microphone volume to mixers

00000: +12dB

... (1.5dB steps)

11111: -34.5dB

5Ch

Additional
Analogue
Functions

Differential Microphone Select

0 : Use MIC1 and MIC2

1: Use LINEL and LINER

Table 3 Microphone Input Control

Note:

The 20dB gain boost acts on the input to the phone mixer only. A separate microphone
boost for recording can be enabled using the BOOST bit in register 1Ah.

MICROPHONE BIAS

The MICBIAS output (pin 28) provides a low noise reference voltage suitable for biasing electret type

microphones and the associated external resistor biasing network. The internal MICBIAS circuitry is

shown below. Note that the maximum source current capability for MICBIAS is 3mA. The external

biasing resistors and microphone cartridge therefore must limit the MICBIAS current to 3mA.

Production Data

WM9712L

PD Rev 4.0 December 2003

AGND

MICBIAS
= 1.8 x CAP2
= 0.9 X AVDD

CAP2

WM9712L

Figure 2 Microphone Bias Schematic

PHONE INPUT

Pin 20 (PHONE) is a mono, line level input designed to connect to the receive path of a telephony

device.

The pin connects directly to the record selector for phone call recording (Note: to record both sides of

a phone call, one ADC channel should record the PHONE signal while the other channel records the

MIC signal). The RECVOL PGA adjusts the recording volume, controlled by register 1Ch or by the

ALC function.

To listen to the PHONE signal, the signal passes through a separate PGA, controlled by register

0Ch. The signal can be routed into the headphone mixer (for normal phone call operation) and/or the

speaker mixer (for speakerphone operation), but not into the phone mixer (to prevent forming a

feedback loop). When the phone input is not used, the phone-in PGA can be switched off to save

power (see "Power Management" section).

PHONE is biased internally to the reference voltage VREF. Whenever the input is muted or the

device placed into standby mode, the input remains biased to VREF using special anti-thump

circuitry to suppress any audible clicks when changing inputs.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

P2H

Mute PHONE path to headphone mixer

1: Mute, 0: No mute (ON)

P2S

Mute PHONE path to speaker mixer

1: Mute, 0: No mute (ON)

0Ch

Phone Input

4:0

PHONE

VOL

01000

(0dB)

PHONE input gain

00000: +12dB

... (1.5dB steps)

11111: -34.5dB

Table 4 Phone Input Control

WM9712L

Production Data

PD Rev 4.0 December 2003

PCBEEP INPUT

Pin 19 (PCBEEP) is a mono, line level input intended for externally generated signal or warning

tones. It is routed directly to the record selector and all three output mixers, without an input

amplifier. The signal gain into each mixer can be independently controlled, with a separate mute bit

for each signal path.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

B2H

Mute PCBEEP path to headphone mixer

1: Mute, 0: No mute (ON)

14:12

B2HVOL

010

(0dB)

PCBEEP to headphone mixer gain

000: +6dB

... (3dB steps)

111: -15dB

B2S

Mute PCBEEP path to speaker mixer

1: Mute, 0: No mute (ON)

10:8

B2SVOL

010

(0dB)

PCBEEP to speaker mixer gain

000: +6dB

... (3dB steps)

111: -15dB

B2P

Mute PCBEEP path to phone mixer

1: Mute, 0: No mute (ON)

0Ah

PCBEEP input

6:4

B2PVOL

010

(0dB)

PCBEEP to phone mixer gain

000: +6dB

... (3dB steps)

111: -15dB

Table 5 PCBEEP Control

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WM9712L

PD Rev 4.0 December 2003

AUDIO ADC

The WM9712L has a stereo sigma-delta ADC to digitize audio signals. The ADC achieves high

quality audio recording at low power consumption. The ADC sample rate can be controlled by writing

to a control register (see "Variable Rate Audio"). It is independent of the DAC sample rate.

To save power, the left and right ADCs can be separately switched off using the PD11 and PD12

bits, whereas PR0 disables both ADCs (see "Power Management" section). If only one ADC is

running, the same ADC data appears on both the left and right AC-Link slots.

HIGH PASS FILTER

The WM9712L audio ADC incorporates a digital high-pass filter that eliminates any DC bias from the

ADC output data. The filter is enabled by default. For DC measurements, it can be disabled by

writing a `1' to the HPF bit (register 5Ch, bit 3).

ADC SLOT MAPPING

By default, the output of the left audio ADC appears on slot 3 of the SDATAIN signal (pin 8), and the

right ADC data appears on slot 4. However, the ADC output data can also be sent to other slots, by

setting the ASS (ADC slot select) control bits as shown below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

1:0

ASS

ADC to slot mapping

00: Left = Slot 3, Right = Slot 4 (default)

01: Left = Slot 7, Right = Slot 8

10: Left = Slot 6, Right = Slot 9

11: Left = Slot 10, Right = Slot 11

5Ch

Additional
Function
Control

HPF

High-pass filter disable

0: Filter enabled (for audio)

1: Filter disabled (for DC measurements)

Table 6 ADC Control

WM9712L

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PD Rev 4.0 December 2003

RECORD SELECTOR

The record selector determines which input signals are routed into the audio ADC. The left and right

channels can be selected independently. This is useful for recording a phone call: one channel can

be used for the RX signal and the other for the TX signal, so that both sides of the conversation are

digitized.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

BOOST

20dB Boost

1: Boost ADC input signal by 20dB

0 :No boost

13:12

R2P

Record to phone path enable

00: Left ADC and Right ADC to phone
mixer

01 : Left ADC to phone mixer

10: Right ADC to phone imixer

11 : Muted

R2PBOOST

20dB Boost for ADC to phone signal

1: Boost signal by 20dB

0 :No boost

10:8

RECSL

000

Left ADC signal source

000: MIC* (pre-PGA)

001-010: Reserved (do not use this setting)

011: Speaker mix

100: LINEINL (pre-PGA)

101: Headphone Mix (left)

110: Phone Mix

111: PHONE (pre-PGA)

1Ah

Record
Select

2:0

RECSR

000

Right ADC signal source

000: MIC* (pre-PGA)

001-010: Reserved (do not use this setting)

011: Speaker mix

100: LINEINR (pre-PGA)

101: Headphone Mix (right)

110: Phone Mix

111: PHONE (pre-PGA)

Table 7 Audio Record Selector

Note:

*In stereo mic mode, MIC1 is routed to the left ADC and MIC2 to the right ADC. In all mono
mic modes, the same signal (MIC1, MIC2 or MIC1-MIC2) is routed to both the left and right
ADCs. See "Microphone Input" section for details.

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RECORD GAIN

The amplitude of the signal that enters the audio ADC is controlled by the Record PGA

(Programmable Gain Amplifier). The PGA gain can be programmed either by writing to the Record

Gain register, or by the Automatic Level Control (ALC) circuit (see next section). When the ALC is

enabled, any writes to the Record Gain register have no effect.

Two different gain ranges can be implemented: the standard gain range defined in the AC'97

standard, or an extended gain range with smaller gain steps. The ALC circuit always uses the

extended gain range, as this has been found to result in better sound quality.

The output of the Record PGA can also be mixed into the phone and/or headphone outputs (see

"Audio Mixers"). This makes it possible to use the ALC function for the microphone signal in a

smartphone application.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

RMU

Mute Audio ADC (both channels)

1: Mute (OFF)

0: No Mute (ON)

GRL

Gain range select (left)

0: Standard (0 to 22.5dB, 1.5dB step size)

1: Extended (-17.25 to +30dB, 0.75dB steps)

Record Volume (left)

Standard (GRL=0)

Extended (GRL=1)

13:8

RECVOLL

000000

XX0000: 0dB

XX0001: +1.5dB

... (1.5dB steps)

XX1111: +22.5dB

000000: -17.25dB

000001: -16.5dB

... (0.75dB steps)

111111: +30dB

Zero Cross Enable

0: Record Gain changes immediately

1: Record Gain changes when signal is zero
or after time-out

GRR

Gain range select (right)

Similar to GRL

1Ch

Record Gain

5:0

RECVOLR

000000

Record Volume (right)

Similar to RECVOLL

Table 8 Record Gain Register

WM9712L

Production Data

PD Rev 4.0 December 2003

AUTOMATIC LEVEL CONTROL

The WM9712L has an automatic level control that aims to keep a constant recording volume

irrespective of the input signal level. This is achieved by continuously adjusting the PGA gain so that

the signal level at the ADC input remains constant. A digital peak detector monitors the ADC output

and changes the PGA gain if necessary.

hold
time

decay

time

attack

time

input

signal

after
ALC

PGA

gain

ALC

target

level

Figure 3 ALC Operation

The ALC function is enabled using the ALCSEL control bits. When enabled, the recording volume

can be programmed between 6dB and 28.5dB (relative to ADC full scale) using the ALCL register

bits.

HLD, DCY and ATK control the hold, decay and attack times, respectively:

Hold time is the time delay between the peak level detected being below target and the PGA gain

beginning to ramp up. It can be programmed in power-of-two (2

) steps, e.g. 2.67ms, 5.33ms,

10.67ms etc. up to 43.7s. Alternatively, the hold time can also be set to zero. The hold time only

applies to gain ramp-up, there is no delay before ramping the gain down when the signal level is

above target.

Decay (Gain Ramp-Up) Time is the time that it takes for the PGA gain to ramp up across 90% of its

range (e.g. from 15B up to 27.75dB). The time it takes for the recording level to return to its target

value therefore depends on both the decay time and on the gain adjustment required. If the gain

adjustment is small, it will be shorter than the decay time. The decay time can be programmed in

power-of-two (2

) steps, from 24ms, 48ms, 96ms, etc. to 24.58s.

Attack (Gain Ramp-Down) Time is the time that it takes for the PGA gain to ramp down across 90%

of its range (e.g. from 27.75dB down to 15B gain). The time it takes for the recording level to return

to its target value therefore depends on both the attack time and on the gain adjustment required. If

the gain adjustment is small, it will be shorter than the attack time. The attack time can be

programmed in power-of-two (2

) steps, from 6ms, 12ms, 24ms, etc. to 6.14s.

When operating in stereo, the peak detector takes the maximum of left and right channel peak

values, and any new gain setting is applied to both left and right PGAs, so that the stereo image is

preserved. However, the ALC function can also be enabled on one channel only. In this case, only

one PGA is controlled by the ALC mechanism, while the other channel runs independently with its

PGA gain set through the control register.

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PD Rev 4.0 December 2003

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

15:14

ALCSEL

(OFF)

ALC function select

00 = ALC off (PGA gain set by register)

01 = Right channel only

10 = Left channel only

11 = Stereo (PGA registers unused)

Note: Ensure that RECVOLL and RECVOLR
settings (reg. 1Ch) are the same before
entering this mode

13:11

MAXGAIN

111

(+30dB)

PGA gain limit for ALC

111 = +30dB

110 = +24dB

....(6dB steps)

001 = -6dB

000 = -12dB

ALCZC

ALC Zero Cross enable (overrides ZC bit in
register 1Ch)

0: PGA Gain changes immediately

1: PGA Gain changes when signal is zero or
after time-out

62h

ALC / Noise
Gate Control

9:10

ZC
TIMEOUT

Programmable zero cross timeout

11 2

x MCLK period

10 2

x MCLK period

01 2

x MCLK period

00 2

x MCLK period

15:12

ALCL

1011

(-12dB)

ALC target sets signal level at ADC input

0000 = -28.5dB FS

0001 = -27.0dB FS

... (1.5dB steps)

1110 = -7.5dB FS

1111 = -6dB FS

11:8

HLD

0000

(0ms)

ALC hold time before gain is increased.

0000 = 0ms

0001 = 2.67ms

0010 = 5.33ms

... (time doubles with every step)

1111 = 43.691s

7:4

DCY

0011

(192ms)

ALC decay (gain ramp-up) time

0000 = 24ms

0001 = 48ms

0010 = 96ms

... (time doubles with every step)

1010 or higher = 24.58s

60h

ALC Control

3:0

ATK

0010

(24ms)

ALC attack (gain ramp-down) time

0000 = 6ms

0001 = 12ms

0010 = 24ms

... (time doubles with every step)

1010 or higher = 6.14s

Table 9 ALC Control

WM9712L

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PD Rev 4.0 December 2003

MAXIMUM GAIN

The MAXGAIN register sets the maximum gain value that the PGA can be set to whilst under the

control of the ALC. This has no effect on the PGA when ALC is not enabled.

PEAK LIMITER

To prevent clipping when a large signal occurs just after a period of quiet, the ALC circuit includes a

limiter function. If the ADC input signal exceeds 87.5% of full scale (1.16dB), the PGA gain is

ramped down at the maximum attack rate (as when ATK = 0000), until the signal level falls below

87.5% of full scale. This function is automatically enabled whenever the ALC is enabled.

(Note: If ATK = 0000, then the limiter makes no difference to the operation of the ALC. It is designed

to prevent clipping when long attack times are used).

NOISE GATE

When the signal is very quiet and consists mainly of noise, the ALC function may cause "noise

pumping", i.e. loud hissing noise during silence periods. The WM9712L has a noise gate function

that prevents noise pumping by comparing the signal level at the input pins (i.e. before the record

PGA) against a noise gate threshold, NGTH. Provided that the noise gate function is enabled (NGAT

= 1), the noise gate cuts in when:

Signal level at ADC [dB] < NGTH [dB] + PGA gain [dB] + Mic Boost gain [dB]

This is equivalent to:

Signal level at input pin [dB] < NGTH [dB]

The PGA gain is then held constant (preventing it from ramping up as it normally would when the

signal is quiet). If the NGG bit is set, the ADC output is also muted when the noise gate cuts in.

The table below summarises the noise gate control register. The NGTH control bits set the noise

gate threshold with respect to the ADC full-scale range. The threshold is adjusted in 1.5dB steps.

Levels at the extremes of the range may cause inappropriate operation, so care should be taken with

setup of the function. Note that the noise gate only works in conjunction with the ALC function, and

always operates on the same channel(s) as the ALC (left, right, both, or none).

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

NGAT

Noise gate function enable

1 = enable

0 = disable

NGG

Noise gate type

0 = PGA gain held constant

1 = mute ADC output

62h

ALC / Noise
Gate Control

4:0

NGTH(4:0)

00000

Noise gate threshold

00000: -76.5dBFS

00001: -75dBFS

... 1.5 dB steps

11110: -31.5dBFS

11111: -30dBFS

Table 10 Noise Gate Control

Production Data

WM9712L

PD Rev 4.0 December 2003

AUDIO DACS

STEREO DAC

The WM9712L has a stereo sigma-delta DAC that achieves high quality audio playback at low power

consumption. Digital tone control, adaptive bass boost and 3-D enhancement functions operate on

the digital audio data before it is passed to the stereo DAC. (Contrary to the AC'97 specification, they

have no effect on analogue input signals or signals played through the auxiliary DAC. Nevertheless,

the ID2 and ID5 bits in the reset register, 00h, are set to `1' to indicate that the WM9712L supports

tone control and bass boost.)

The DAC output has a PGA for volume control. The DAC sample rate can be controlled by writing to

a control register (see "Variable Rate Audio"). It is independent of the ADC sample rate. The left and

right DACs can be separately powered down using the PD13 and PD14 control bits, whereas the

PR1 bit disables both DACs (see "Power Management" section).

STEREO DAC VOLUME

The volume of the DAC output signal is controlled by a PGA (Programmable Gain Amplifier). It can

be mixed into the headphone, speaker and phone output paths (see "Audio Mixers").

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

D2H

Mute DAC path to headphone mixer

1: Mute, 0: No mute (ON)

D2S

Mute DAC path to speaker mixer

1: Mute, 0: No mute (ON)

D2P

Mute DAC path to phone mixer

1: Mute, 0: No mute (ON)

12:8

DACL

VOL

01000

(0dB)

Left DAC Volume

00000: +12dB

... (1.5dB steps)

11111: -34.5dB

18h

DAC
Volume

4:0

DACR

VOL

01000

(0dB)

Right DAC Volume

similar to DACLVOL

AMUTE

Read-only bit to indicate auto-muting

1: DAC auto-muted

0: DAC not muted

5Ch

Additional
Functions
(1)

AMEN

DAC Auto-Mute Enable

1: Automatically mutes analogue output of
stereo DAC if digital input is zero

0: Auto-mute OFF

Table 11 Stereo DAC Volume Control

WM9712L

Production Data

PD Rev 4.0 December 2003

TONE CONTROL / BASS BOOST

The WM9712L provides separate controls for bass and treble with programmable gains and filter

characteristics. This function operates on digital audio data before it is passed to the audio DACs.

Bass control can take two different forms:

Linear bass control: bass signals are amplified or attenuated by a user programmable
gain. This is independent of signal volume, and very high bass gains on loud signals
may lead to signal clipping.

Adaptive bass boost: The bass volume is amplified by a variable gain. When the bass
volume is low, it is boosted more than when the bass volume is high. This method is
recommended because it prevents clipping, and usually sounds more pleasant to the
human ear.

Treble control applies a user programmable gain, without any adaptive boost function.

Treble, linear bass and 3D enhancement can all produce signals that exceed full-scale. In order to

avoid limiting under these conditions, it is recommended to set the DAT bit to attenuate the digital

input signal by 6dB. The gain at the outputs should be increased by 6dB to compensate for the

attenuation. Cut-only tone adjustment and adaptive bass boost cannot produce signals above full-

scale and therefore do not require the DAT bit to be set.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Bass Mode

0 = Linear bass control

1 = Adaptive bass boost

Bass Cut-off Frequency

0 = Low (130Hz at 48kHz sampling)

1 = High (200Hz at 48kHz sampling)

Bass Intensity

Code

BB=0

BB=1

0000

+9dB

15 (max)

0001

+9dB

0010

+7.5dB

...

(1.5dB steps)

...

0111

0dB

...

(1.5dB steps)

...

1011-1101

-6dB

4-2

1110

-6dB

1 (min)

11:8

BASS

1111
(OFF)

1111

Bypass (OFF)

DAT

-6dB attenuation

0 = Off

1 = On

Treble Cut-off Frequency

0 = High (8kHz at 48kHz sampling)

1 = Low (4kHz at 48kHz sampling)

08h

DAC Tone
Control

3:0

TRBL

1111
(Disabled)

Treble Intensity

0000 or 0001 = +9dB

0010 = +7.5dB

... (1.5dB steps)

1011 to 1110 = -6dB

1111 = Treble Control Disabled

Table 12 DAC Tone Control

Note:

All cut-off frequencies change proportionally with the DAC sample rate.

Production Data

WM9712L

PD Rev 4.0 December 2003

3D STEREO ENHANCEMENT

The 3D stereo enhancement function artificially increases the separation between the left and right

channels by amplifying the (L-R) difference signal in the frequency range where the human ear is

sensitive to directionality. The programmable 3D depth setting controls the degree of stereo

expansion introduced by the function. Additionally, the upper and lower limits of the frequency range

used for 3D enhancement can be selected using the 3DFILT control bits.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

20h

General
Purpose

3DE

0
(disabled)

3D enhancement enable

3DLC

Lower Cut-off Frequency

0 = Low (200Hz at 48kHz sampling)

1 = High (500Hz at 48kHz sampling)

3DUC

Upper Cut-off Frequency

0 = High (2.2kHz at 48kHz sampling)

1 = Low (1.5kHz at 48kHz sampling)

22h

DAC 3D
Control

3:0

3DDEPTH

0000

3D Depth

0000: 0% (minimum 3D effect)

0001: 6.67%

...

1110: 93.3%

1111: 100% (maximum)

Table 13 Stereo Enhancement Control

Note:

All cut-off frequencies change proportionally with the DAC sample rate.

WM9712L

Production Data

PD Rev 4.0 December 2003

AUXILIARY DAC

AUXDAC is a simple 12-bit mono DAC. It can be used to generate DC signals (with the numeric input

written into a control register), or AC signals such as telephone-quality ring tones or system beeps

(with the input signal supplied through an AC-Link slot). In AC mode (XSLE = 1), the input data is

binary offset coded; in DC mode (XSLE = 0), there is no offset.

The analogue output of AUXDAC is routed directly into the output mixers. The signal gain into each

mixer can be adjusted at the mixer inputs using control register 12h. In slot mode (XSLE = 1), the

AUXDAC also supports variable sample rates (See "Variable Rate Audio" section).

When the auxiliary DAC is not used, it can be powered down by setting AXE = 0. This is also the

default setting.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

XSLE

AUXDAC input selection

0: from AUXDACVAL (for DC signals)

1: from AC-Link slot selected by
AUXDACSLT (for AC signals)

14:12

AUXDAC

SLT

000

AUXDAC Input Selection

000 Slot 5, bits 8-19 (with XSLE=1)

001 Slot 6, bits 8-19 (with XSLE=1)

010 Slot 7, bits 8-19 (with XSLE=1)

011 Slot 8, bits 8-19 (with XSLE=1)

100 Slot 9, bits 8-19 (with XSLE=1)

101 Slot 10, bits 8-19 (with XSLE=1)

110 Slot 11, bits 8-19 (with XSLE=1)

111 RESERVED (do not use)

64h

AUDAC Input
Control

11:0

AUXDAC

VAL

000h

AUXDAC Digital Input (with XSLE=0)

000h: minimum

FFFh: full-scale

A2H

Mute AUXDAC path to headphone
mixer

1: Mute, 0: No mute (ON)

14:12

A2HVOL

010

(0dB)

AUXDAC to headphone mixer gain

000: +6dB

... (3dB steps)

111: -15dB

A2S

Mute AUXDAC path to speaker mixer

1: Mute, 0: No mute (ON)

10:8

A2SVOL

010

(0dB)

AUXDAC to speaker mixer gain

000: +6dB

... (3dB steps)

111: -15dB

A2P

Mute AUXDAC path to phone mixer

1: Mute, 0: No mute (ON)

6:4

A2PVOL

010

(0dB)

AUXDAC to phone mixer gain

000: +6dB

... (3dB steps)

111: -15dB

12h

AUXDAC Output
Control

AXE

0: AUXDAC off

1: AUXDAC enabled

Table 14 AUXDAC Control

Production Data

WM9712L

PD Rev 4.0 December 2003

ANALOGUE AUDIO OUTPUTS

The following sections give an overview of the analogue audio output pins. For more information on

recommended external components, please refer to the "Applications Information" section.

HEADPHONE OUTPUTS HPOUTL AND HPOUTR

The HPOUTL and HPOUTR (pins 39 and 41) are designed to drive a 16

or 32

headphone or a

line output. They can also be used as line-out pins. The output signal is produced by the headphone

mixer.

The signal volume on HPOUTL and HPOUTR can be independently adjusted under software control

by writing to register 04h. When HPOUTL and HPOUTR are not used, the output drivers can be

disabled to save power (see "Power Management" section). Both pins remain at the same DC level

(the reference voltage VREF) when they are disabled, so that no click noise is produced.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

MUTE

Mute HPOUTL and HPOUTR

1: Mute (OFF)

0: No Mute (ON)

13:8

HPOUTLVOL

000000

(0dB)

HPOUTL Volume

000000: 0dB (maximum)

000001: -1.5dB

... (1.5dB steps)

011111: -46.5dB

1xxxxx: -46.5dB

Zero Cross Enable

0: Change gain immediately

1: Change gain only on zero crossings,
or after time-out

04h

HPOUTL /
HPOUTR

Volume

5:0

HPOUTRVOL

00000

(0dB)

HPOUTR Volume

Similar to HPOUTLVOL

Table 15 HPOUTL / HPOUTR Control

WM9712L

Production Data

PD Rev 4.0 December 2003

EAR SPEAKER OUTPUT OUT3

Pin 37 (OUT3) has a buffer that can drive load impedances down to 16

. It can be used to:

Drive an ear speaker (phone receiver). The speaker can be connected differentially
between OUT3 and HPOUTL, or in single-ended configuration (OUT3 to HPGND). The
ear speaker output is produced by the headphone mixer. The right signal must be
inverted (OUT3INV = 1), so that the left and right channel are mixed to mono in the
speaker [L(-R) = L+R].

Eliminate the DC blocking capacitors on HPOUTL and HPOUTR. In this configuration,
OUT3 produces a buffered midrail voltage (AVDD/2) and is connected to the headphone
socket's ground pin (see "Applications Information")

Produce the inverse of the MONOOUT signal, for a differential mono output.

Note: OUT3 can only handle one of the above functions at any given time.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

MUTE

Mute OUT3

1: Mute (Buffer OFF)

0: No Mute (Buffer ON)

Source of OUT3 signal

inverse of HPOUTR

(for BTL ear speaker)

VREF (for capless headphone drive)

mono mix of both headphone channels
(for single-ended ear speaker)

10:9

OUT3
SRC

inverse of MONOOUT

(for differential mono output)

Zero Cross Enable

0: Change gain immediately

1: Change gain only on zero crossings, or after
time-out

16h

OUT3

Control

5:0

OUT3
VOL

000000

(0dB)

OUT3 Volume

000000: 0dB (maximum)

000001: -1.5dB

... (1.5dB steps)

011111: -46.5dB

1xxxxx: -46.5dB

Table 16 OUT3 Control

Production Data

WM9712L

PD Rev 4.0 December 2003

LOUDSPEAKER OUTPUTS LOUT2 AND ROUT2

The LOUT2 and ROUT2 outputs are designed to differentially drive an 8

mono speaker. They can

also be used as a stereo line-out or headphone output.

For speaker drive, the LOUT2 signal must be inverted (INV = 1), so that the left and right channel are

added up in the speaker [R(-L) = R+L].

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

MUTE

Mute LOUT2 and ROUT2

1: Mute (OFF)

0: No Mute (ON)

13:8

LOUT2VOL

00000

(0dB)

LOUT2 Volume

000000: 0dB (maximum)

000001: -1.5dB

... (1.5dB steps)

011111: -46.5dB

1xxxxx: -46.5dB

Zero Cross Enable

0: Change gain immediately

1: Change gain only on zero crossings,
or after time-out

INV

LOUT2 Invert

0 = No Inversion (0

phase shift)

1 = Signal inverted (180

phase shift)

02h

LOUT2/ROUT2

Volume

5:0

ROUT2VOL

00000

(0dB)

ROUT2 Volume

Similar to LOUT2VOL

16h

SRC

Source of LOUT2/ROUT2 signals

0: speaker mixer (for BTL speaker)

1: headphone mixer (for stereo output)

Table 17 LOUT2 / ROUT2 Control

Note:

For BTL speaker drive, it is recommended that LOUT2VOL = ROUT2VOL.

WM9712L

Production Data

PD Rev 4.0 December 2003

PHONE OUTPUT (MONOOUT)

The MONOOUT output (pin 33) is intended for connection to the TX side of a wireless chipset. The

signal is generated in a dedicated mono mixer; it is not necessarily a mono mix of the stereo outputs

HPOUTL/R or LOUT2/ROUT2 (see "Audio Mixers" section).

The MONOOUT volume can be controlled by writing to register 06h. When MONOOUT is not used,

the output buffer can be disabled to save power (see "Power Management" section). The MONOOUT

pin remains at the same DC level (the reference voltage on the VREF pin), so that no click noise is

produced when muting or un-muting.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

MUTE

Mute MONOOUT

1: Mute

0: No Mute

Zero Cross Enable

0: Change gain immediately

1: Change gain only on zero crossings,
or after time-out

06h

MONOOUT

Volume

4:0

MONOOUT
VOL

00000

(0dB)

MONOOUT Volume

00000: 0dB (maximum)

00001: -1.5dB

... (1.5dB steps)

11111: -46.5dB

Table 18 MONOOUT Control

THERMAL SENSOR

The speaker and headphone outputs can drive very large currents. To protect the WM9712L from

becoming too hot, a thermal sensor has been built in. If the chip temperature reaches approximately

150

C, and the ENT bit is set, the WM9712L deasserts GPIO bit 11 in register 54h, a virtual GPIO

that can be set up to generate an interrupt to the CPU (see "GPIO and Interrupt Control" section).

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

5Ch

ENT

Enable thermal sensor

0: Disabled

1: Enabled

54h

Thermal sensor (virtual GPIO)

1: Temperature below 150

0: Temperature above 150

See also "GPIO and Interrupt Control" section.

Table 19 Thermal Cutout Control

Production Data

WM9712L

PD Rev 4.0 December 2003

JACK INSERTION AND AUTO-SWITCHING

In a phone application, a BTL ear speaker may be connected across OUT3 and HPOUTL, and a

stereo headphone on HPOUTL and HPOUTR. Typically, only one of these two output devices is

used at any given time: when no headphone is plugged in, the BTL ear speaker is active, otherwise

the headphone is used.

The presence of a headphone can be detected using GPIO1 (pin 44) and an external pull-up resistor

(see "Applications Information" section for a circuit diagram). When the jack is inserted GPIO1 is

pulled low by a switch on the socket. When the jack is removed GPIO1 is pulled high by a resistor. If

the JIEN bit is set, the WM9712L automatically switches between headphone and ear speaker, as

shown below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

JIEN

Jack Insert Enable Takes output of GPIO1
logic

58h
Additional
Functional
Control

FRC

Force Ear Speaker Mode

See table below

Table 20 Jack Insertion / Auto-Switching (1)

JIEN FRC GPIO1

MODE DESCRIPTION

HPO

VOL

HPO

VOL

HPOU

TL/

HPO

Jack insert detection disabled
(headphone and ear speaker
can be used at the same
time)

Set by
reg.
24h
and
26h

Jack insert detection
enabled, headphone plugged
in

Dis

abl

eg.

04h

Jack insert detection
enabled, headphone not
plugged in

Force Ear Speaker Mode

Set by
reg.
24h
and
26h

Set by
reg.
16h

t

by

r
eg.

04h

t

by

r
eg.

16h

t

by

r
eg.

24h

and 26h

Invalid; do not use this setting

Table 21 Jack Insertion / Auto-Switching (2)

WM9712L

Production Data

PD Rev 4.0 December 2003

DIGITAL AUDIO (SPDIF) OUTPUT

The WM9712L supports the SPDIF standard using pin 47 as its output. Note that pin 47 can also be

used as a GPIO pin. The GE5 bit (register 56h, bit 5) selects between GPIO and SPDIF functionality

(see "GPIO and Interrupt control" section).

propagated as channel status (or sub-frame in the V case). With the exception of V, this register

should only be written to when the SPDIF transmitter is disabled (SPDIF bit in register 2Ah is `0').

Once the desired values have been written to this register, the contents should be read back to

ensure that the sample rate in particular is supported, then SPDIF validity bit SPCV in register 2Ah

should be read to ensure the desired configuration is valid. Only then should the SPDIF enable bit in

beginning of SPDIF transmission.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

SPCV

SPDIF validity bit (read-only)

5:4

SPSA

SPDIF slot assignment (ADCO = 0)

00: Slots 3, 4

01: Slots 6, 9

10: Slots 7, 8

11: Slots 10, 11

2Ah

Extended
Audio

SEN

SPDIF output enable

1 = enabled, 0 = disabled

Validity bit; `0' indicates frame valid, `1'
indicates frame not valid

DRS

Indicates that the WM9712L does not support
double rate SPDIF output (read-only)

13:12

SPSR

Indicates that the WM9712L only supports
48kHz sampling on the SPDIF output (read-
only)

Generation level; programmed as required by
user

10:4

0000000

Category code; programmed as required by
user

PRE

Pre-emphasis; `0' indicates no pre-emphasis,
`1' indicates 50/15us pre-emphasis

COPY

AUDIB

Non-audio; `0' indicates data is PCM, `1'
indicates non-PCM format (e.g. DD or DTS)

3Ah

SPDIF
Control
Register

PRO

Professional; `0' indicates consumer, `1'
indicates professional

5Ch

Additional
Function
Control

ADCO

Source of SPDIF data

0: SPDIF data comes from SDATAOUT (pin
5), slot selected by SPSA

1: SPDIF data comes from audio ADC

Table 22 SPDIF Output Control

Production Data

WM9712L

PD Rev 4.0 December 2003

AUDIO MIXERS

MIXER OVERVIEW

The WM9712L has three separate low-power audio mixers to cover all audio functions required by

smartphones, PDAs and handheld computers. The diagram below shows the routing of the analogue

audio signals into the mixers. The numbers at the mixer inputs refer to the control register bits that

control the volume and muting for that particular signal.

PHONE_IN

PCBEEP

LINE_IN

Stereo

headphone /

headset

HPOUTL

HPOUTR

HPVOL

(Reg 04h)

MONOOUT
(PHONE TX)

OUT3VOL

(Reg 16h)

LOUT2

ROUT2

OUT2VOL

(Reg 02h)

loud

speaker

OUT3

ear

speaker

0Ch [4:0]

10h [12:8,4:0]

18h [12:8,4:0]

RECORD

SELECT

0Eh [12:8,4:0]

MICR

MICL

DIFF /

STEREO/

MONO

(Reg 20h)

STEREO

DAC

AUX
DAC

(12-BIT)

1Ch / ALC

0/20

0Eh [7]

M
U
X

MONOOUT

VREF

18h [15]

10h [15]

14h [15:12]

14h [11:7]

0Ch [15]

12h [15:12]

18h [13]

10h [13]

0Eh [14,13]

1Ah [13:11]

0Ah [15:12]

HEAD

PHONE/

EAR

SPEAKER

MIX

PHONE

MIX

12h [7:4]

0Ah [7:4]

-1

M
U
X

12h [11:8]

18h [14]

10h [14]

0Ah [11:8]

0Ch [14]

BACK

SPEAKER

MIX

SRC

(Reg 16h)

OUT3SRC

(Reg 16h)

STEREO

ADC

M
U
X

PHONE MIX

HEADPHONE MIX

BACK SPKR MIX

INV

(Reg 02h)

1Ah [14]

0/20

Figure 4 Audio Mixer Overview

HEADPHONE MIXER

The headphone mixer drives the HPOUTL and HPOUTR outputs. It also drives OUT3, if this pin is

connected to an ear speaker (phone receiver). The following signals can be mixed into the

headphone path:

PHONE (controlled by register 0Ch, see "Audio Inputs")

LINE_IN (controlled by register 10h, see "Audio Inputs")

the output of the Record PGA (see "Audio ADC", "Record Gain")

the stereo DAC signal (controlled by register 18h, see "Audio DACs")

the MIC signal (controlled by register 0Eh, see "Audio Inputs")

PC_BEEP (controlled by register 0Ah, see "Audio Inputs")

the AUXDAC signal (controlled by register 12h, see "Auxiliary DAC")

In a typical smartphone application, the headphone signal is a mix of PHONE and sidetone (for

phone calls) and the stereo DAC signal (for music playback).

WM9712L

Production Data

PD Rev 4.0 December 2003

SPEAKER MIXER

The speaker mixer drives the LOUT2 and ROUT2 output. The following signals can be mixed into the

speaker path:

PHONE (controlled by register 0Ch, see "Audio Inputs")

LINE_IN (controlled by register 10h, see "Audio Inputs")

the stereo DAC signal (controlled by register 18h, see "Audio DACs")

PC_BEEP (controlled by register 0Ah, see "Audio Inputs")

the AUXDAC signal (controlled by register 12h, see "Auxiliary DAC")

In a typical smartphone application, the speaker signal is a mix of AUXDAC (for system alerts or ring

tone playback), PHONE (for speakerphone function), and PC_BEEP (for externally generated ring

tones).

MONO MIXER

The mono mixer drives the MONOOUT pin. The following signals can be mixed into MONOOUT:

LINE_IN (controlled by register 10h, see "Audio Inputs")

the output of the Record PGA (see "Audio ADC", "Record Gain")

the stereo DAC signal (controlled by register 18h, see "Audio DACs")

the MIC signal (controlled by register 10h, see "Audio Inputs")

PC_BEEP (controlled by register 0Ah, see "Audio Inputs")

the AUXDAC signal (controlled by register 12h, see "Auxiliary DAC")

In a typical smartphone application, the MONOOUT signal is a mix of the amplified microphone

signal (possibly with Automatic Gain Control) and (if enabled) an audio playback signal from the

stereo DAC or the auxiliary DAC.

SIDE TONE CONTROL

The side tone path is into the headphone mixer and is either from the MIC or ALC path (with no 20dB

boost)

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

STM

MIC side tone select

0: selected

1 : not selected (path muted)

14:12

STVOL

010

(0dB)

MIC Sidetone volume

000 : +6dB (max.)

001: +3dB

... (3dB steps)

111 : -15dB (min.)

11:10

ALCM

ALC side tone select

11: mute

10: mono left

01: mono right

00: stereo

14h

Sidetone

Control

9:7

ALCVOL

010

(0dB)

ALC Sidetone volume

Similar to STVOL

Table 23 Side Tone Control

Production Data

WM9712L

PD Rev 4.0 December 2003

VARIABLE RATE AUDIO / SAMPLE RATE CONVERSION

By using an AC'97 Rev2.2 compliant audio interface, the WM9712L can record and playback at all

commonly used audio sample rates, and offer full split-rate support (i.e. the DAC, ADC and

AUXDAC sample rates are completely independent of each other any combination is possible).

The default sample rate is 48kHz. If the VRA bit in register 2Ah is set and the appropriate block is

enabled, then other sample rates can be selected by writing to registers 2Ch, 32h and 2Eh. The AC-

Link continues to run at 48k frames per second irrespective of the sample rate selected. However, if

the sample rate is less than 48kHz, then some frames do not carry an audio sample.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

2Ah

Extended
Audio
Stat/Ctrl

VRA

0 (OFF)

Variable Rate Audio

0: OFF (DAC and ADC run at 48kHz)

1: ON (sample rates determined by
registers 2Ch, 2Eh and 32h)

2Ch

Audio DAC
Sample Rate

15:0

DACSR

BB80h

(48kHz)

Audio DAC sample rate

1F40h: 8kHz

2B11h: 11.025kHz

2EE0h: 12kHz

3E80h: 16kHz

5622h: 22.05kHz

5DC0h: 24kHz

7D00h: 32kHz

AC44h: 44.1kHz

BB80h: 48kHz

Any other value defaults to the nearest
supported sample rate

32h

Audio ADC
Sample Rate

15:0

ADCSR

BB80h

(48kHz)

Audio ADC sample rate

similar to DACSR

2Eh

AUXDAC
Sample Rate

15:0

AUXDA
CSR

BB80h
(48kHz)

AUXDAC sample rate

similar to DACSR

Table 24 Audio Sample Rate Control

WM9712L

Production Data

PD Rev 4.0 December 2003

TOUCHPANEL INTERFACE

The WM9712L includes a touchpanel driver and digitiser circuit for use with 4-wire or 5-wire resistive

touchpanels. The following functions are implemented:

X co-ordinate measurement

Y co-ordinate measurement

Pen down detection, with programmable sensitivity

Touch pressure measurement (4-wire touchpanel only)

Auxiliary measurement from COMP1/AUX1 (pin 29), COMP2/AUX2 (pin 30),
BMON/AUX3 (pin 31), or WIPER/AUX4 (pin 12)

The touchpanel digitiser uses a very low power, 12-bit successive approximation type ADC. The

same ADC can also be used for battery and auxiliary measurements (see the "Battery Alarm and

Battery Measurement" and "Auxiliary ADC Inputs" sections).

An on-chip switch matrix connects each touchpanel terminal to the supply voltage TPVDD, to ground

(TPGND), or to the ADC input, as required.

SAR
ADC

(
14)

-
/T

L (16)

/TR

(15)

-
/B

L (17)

I
PE

(
1

)

/
B

(
3

)

zero power

comparator

TPVD

PEN

DOWN

(
3

)

(
2

)

20K

10K

Figure 5 Touchpanel Switch Matrix

PRINCIPLE OF OPERATION - FOUR-WIRE TOUCHPANEL

Four-wire touchpanels are connected to the WM9712L as follows:

Right side contact = X+ (pin 14)

Left side contact = X- (pin 16)

Top side contact = Y+ (pin 15)

Bottom side contact = Y- (pin 17)

Production Data

WM9712L

PD Rev 4.0 December 2003

The principle of operation is illustrated below (Note: the illustrations assume that the top plate is used

for X and the bottom plate for Y measurements, although the reverse is also possible).

Y+ (15)

X+

(14)

Y- (17)

X- (16)

X+

Y-

pen / finger

Y+

X-

= (V

REF+

- V

REF-

) R

X-

/ (R

X-

+ R

X+

)

= proportional to X position

ADC

REF+

REF-

TPVDD

TPGND

WM9712

Figure 6 X Co-ordinate Measurement on 4-wire Touchpanel

For an X co-ordinate measurement, the X+ pin is internally switched to VDD and X- to GND. The X

plate becomes a potential divider, and the voltage at the point of contact is proportional to its X co-

ordinate. This voltage is measured on the Y+ and Y- pins, which carry no current (hence there is no

voltage drop in R

Y+

or R

Y-

Due to the ratiometric measurement method, the supply voltage does not affect measurement

accuracy. The voltage references VREF+ and VREF- are taken from after the matrix switches, so

that any voltage drop in these switches has no effect on the ADC measurement.

Y+ (15)

X+

(14)

Y- (17)

X- (16)

X+

Y-

pen / finger

Y+

X-

= (V

REF+

- V

REF-

) R

Y-

/ (R

Y-

+ R

Y+

)

= proportional to Y position

ADC

REF+

REF-

TPVDD

TPGND

WM9712

Figure 7 Y Co-ordinate Measurement on 4-wire Touchpanel

Y co-ordinate measurements are similar to X co-ordinate measurements, with the X and Y plates

interchanged.

zero power
comparator

Y+ (15)

X+

(14)

Y- (17)

X- (16)

X+

Y-

pen / finger

Y+

X-

TPGND

WM9712

PEN
DOWN

TPVDD

Figure 8 Pen Down Detection on 4-wire Touchpanel

Pen down detection uses a zero power comparator (effectively a CMOS logic gate) with an internal,

programmable pull-up resistor R

that controls pen-down sensitivity. Increasing R

makes the

touchpanel less sensitive to touch, while lowering R

makes it more sensitive.

WM9712L

Production Data

PD Rev 4.0 December 2003

When the touchpanel is not being touched, no current flows in the circuit, and the PENDOWN signal

is low. When the panel is touched with a pen or finger, current flows through R

and the panel, and

the comparator output goes high.

The PENDOWN signal can be read from bit 15 in register 7Ah (labeled PNDN). It can also be

observed on pin 46 (GPIO3 / PENDOWN), if the pin is not used for GPIO (GE3=0). Additionally,

PENDOWN is passed to the GPIO logic block (register 54h, bit 13), where it can generate CPU

interrupts, and / or to wake up the WM9712L from sleep mode (see "GPIO and Interrupt Control"

section).

Y+ (15)

X+

(14)

Y- (17)

X- (16)

X+

Y-

pen / finger

Y+

X-

TPGND

WM9712

TPVDD

ADC

Y-

- V

X+

= I

= proportional to contact resistance

Figure 9 Touch Pressure Measurement on 4-wire Touchpanel

Touch pressure can be determined indirectly by measuring the contact resistance R

between the

top and bottom plates. R

decreases as the touch pressure on the panel increases. The WM9712L

measures R

by sending a constant current I

through the touchpanel and measuring the potential

on each plate. The two values are subtracted in the digital domain to obtain the potential difference,

which is proportional to R

To suit different types of touchpanels, the magnitude of I

can be set to either 400

A or 200

A using

the PIL control bit.

PRINCIPLE OF OPERATION - FIVE-WIRE TOUCHPANEL

Five-wire touchpanels are connected to the WM9712Las follows:

Top sheet contact = WIPER/AUX4 (pin 12)

Top left corner of bottom sheet = TL (pin 16)

Top right corner of bottom sheet = TR (pin 15)

Bottom left corner of bottom sheet = BL (pin 17)

Bottom right corner of bottom sheet = BR (pin 14)

= proportional to X position

WM9712

WIPER (12)

TR (15)

ADC

REF+

REF-

TPGND

TPVDD

BR (14)

BL (17)

TL (16)

Figure 10 X Co-ordinate Measurement on 5-wire Touchpanel

Production Data

WM9712L

PD Rev 4.0 December 2003

For an X co-ordinate measurement, the top left and bottom left corners of the touchpanel are

grounded internally to the WM9712, while the top right and bottom right contacts are connected to

TPVDD. The bottom plate becomes a potential divider with a voltage gradient in the X direction. The

voltage at the point of contact is proportional to its X co-ordinate. This voltage is measured on the

TOP pin and converted to a digital value by the ADC.

Due to the ratiometric measurement method, the supply voltage does not affect measurement

accuracy. The voltage references VREF+ and VREF- are taken from after the matrix switches, so

that any voltage drop in these switches has no effect on the ADC measurement.

= proportional to Y position

WM9712

WIPER (12)

TR (15)

ADC

REF+

REF-

TPGND

TPVDD

TPGND

TPVDD

BR (14)

BL (17)

TL (16)

Figure 11 Y Co-ordinate Measurement on 5-wire Touchpanel

Y co-ordinate measurements are similar to Y co-ordinate measurements. However, the voltage

gradient on the bottom plate is in the Y direction instead of the X direction. This is achieved by

grounding the bottom left and bottom right corners of the touchpanel, and connecting the top left and

top right contacts to TPVDD.

WM9712

WIPER (12)

TR (15)

TPGND

BR (14)

BL (17)

TL (16)

zero power
comparator

VDD

PEN
DOWN

Figure 12 Pen Down Detection on 5-wire Touchpanel

Pen down detection works in a similar fashion for both 4-wire and 5-wire touchpanels (see Four-Wire

Touchpanel Operation). On a 5-wire touchpanel, all four contacts of the bottom plate are grounded,

and the top plate contact is connected to the internal programmable pull-up resistor, R

WM9712L

Production Data

PD Rev 4.0 December 2003

CONTROLLING THE TOUCHPANEL DIGITISER

All touchpanel functions are accessed and controlled through the AC-Link interface.

PHYSICAL CHARACTERISTICS

The physical characteristics of the touchpanel interface are controlled through register 78, as shown

below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

45W

0 (4-wire)

Touchpanel Type Selection

0: 4-wire

1: 5-wire

0:5

RPU

000001

(64k

)

Internal Pull-up resistor for Pen Detection

000000: RESERVED (do not use this setting)

000001: R

/1 = TYP 64k

(most sensitive)

000010: R

/2 = TYP 32k

... (pull-up = R

/ binary value of RPU)

(Refer to page 9 for R

specification)

78h

PIL

0 (200

Current used for pressure measurement

0: I

= 200

1: I

= 400

Table 25 Touchpanel Digitiser Control (Physical Characteristics)

POWER MANAGEMENT

To save power, the touchpanel digitiser and the pen-down detector can be independently disabled

when they are not used. The power consumption of the pen-down detector is normally negligible,

except when the pen is down.

The state of the digitiser and pen down detector is controlled by the following bits.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

15:14

PRP

Pen ADC/AUX ADC enable

00 Pen digitiser off, pen detect off, no
wake-up on pen down (default)

01 Pen digitiser powered off, pen detect
enabled, touchpanel digitiser wakes up
(changes to state 11) on pen-down

10 Pen digitiser off, pen detect enabled,
no wake-up on pen down

11 Pen digitiser and pen detect enabled

78h

RPR

Wake-up on pen-down mode

0: Wake-up the AC-Link only (hold
SDATAIN high until controller sends warm
reset or cold reset)

1: Wake-up the WM9712L without waiting
for a reset signal from the controller

Table 26 Touchpanel Digitiser Control (Power Management)

Production Data

WM9712L

PD Rev 4.0 December 2003

INITIATION OF MEASUREMENTS

The WM9712L touchpanel interface supports both polling routines and DMA (direct memory access)

to control the flow of data from the touchpanel ADC to the host CPU.

In a polling routine, the CPU starts each measurement individually by writing to the POLL bit (register

76h, bit 15). This bit automatically resets itself when the measurement is completed.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

CTC

0: Polling mode

1: Continuous mode (for DMA)

POLL

Writing "1" initiates a measurement

76h

9:8

Continuous mode rate (DEL 1111)

00: 93.75 Hz (every 512 AC-Link frames)

01: 187.5 Hz (every 256 AC-Link frames)

10: 375Hz (every 128 AC-Link frames)

11: 750Hz (every 64 AC-Link frames)

Continuous mode rate (DEL = 1111)

00: 8 kHz (every six AC-Link frames)

01: 12 kHz (every four AC-Link frames)

10: 24 kHz (every other AC-Link frame)

11: 48 kHz (every AC-Link frame)

78h

PDEN

0: measure regardless of pen status

1: measure only when pen is down (when
CTC=0 and POLL=1, measurement is
delayed until pen-down; when CTC=1,
measurements are stopped on pen-up)

Table 27 Touchpanel Digitiser Control (Initiation of Measurements)

In continuous mode (CTC = 1), the WM9712L autonomously initiates measurements at the rate set

by CR, and supplies the measured data to the CPU on one of the unused AC'97 time slots. DMA-

enabled CPUs can write the data directly into a FIFO without any intervention by the CPU core. This

reduces CPU loading and speeds up the execution of user programs in handheld systems.

Note that the measurement frequency in continuous mode is also affected by the DEL bits (see

"Touchpanel Settling Time"). The faster rates achieved when DEL = 1111 may be useful when the

ADC is used for auxiliary measurements.

MEASUREMENT TYPES

The ADCSEL control bits determine which type of measurement is performed (see below).

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

14:12

ADCSEL

000

Measurement Type (ADC Input Selector)

000: No measurement

001: X co-ordinate measurement

010: Y co-ordinate measurement

011: Pressure measurement

100: COMP1/AUX1 measurement (pin 29)

101: COMP2/AUX2 measurement (pin 30)

110: BMON/AUX3 measurement (pin 31)

111: WIPER/AUX4 measurement (pin 12)

76h

COO

Enable co-ordinate mode

0: Single measurement according to ADCSEL

1: X, then Y, then additional measurement
indicated by ADCSEL

Table 28 Touchpanel Digitiser Control (Measurement Types)

WM9712L

Production Data

PD Rev 4.0 December 2003

When COO is `0', the WM9712L performs one type of measurement once (in polling mode) or

continuously (in continuous mode).

The co-ordinate mode (COO = `1') makes it easier to obtain co-ordinate pairs rather than single co-

ordinates. In polling-coordinate mode (CTC = `0', COO = `1'), the WM9712L performs an X

measurement, followed by a Y measurement, followed by an additional measurement determined by

ADCSEL, then stops. In continuous-coordinate mode (CTC = `1', COO = `1'), the WM9712L

continuously repeats a sequence consisting of an X-co-ordinate measurement, followed by a Y co-

ordinate measurement, followed by an additional measurement determined by ADCSEL (if ADCSEL

= 000, the sequence is XYXYXY... only).

DATA READBACK

The output data word of the touchpanel interface consists of three parts:

Pen Status (1 bit) this is also passed to the GPIO logic block, which can be
programmed to generate an interrupt and/or wake up the WM9712L on pen down (see
GPIO and Interrupt Control).

Output data from the touchpanel ADC (12 bits)

ADCSRC: 3 additional bits that indicate the source of the ADC data. With COO = `0',
ADCSRC echoes ADCSEL. However, in co-ordinate mode (COO = `1'), the WM9712L
schedules different types of measurements autonomously and sets the ADCSRC bits
accordingly (see "Measurement Types").

This data is stored in register 7Ah, and can be retrieved by reading the register in the usual manner

(see AC-Link Interface section). Additionally, the data can also be passed to the controller on one of

the AC-Link time slots not used for audio functions.

If the data is being read back using the polling method, there are several ways to determine when a

measurement has finished:

Reading back the POLL bit. If it has been reset to `0', then the measurement has finished.

By monitoring the ADA signal, see GPIO and interrupt section

Reading back 7Ah until the new data appears

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

PNDN

Pen status (read-only)

0: Pen Up

1: Pen Down

14:12

ADCSRC

000

Touchpanel ADC Source

000: No measurement

001: X co-ordinate measurement

010: Y co-ordinate measurement

011: Pressure measurement

(4-wire touchpanels only)

100: COMP1/AUX1 measurement (pin 29)

101: COMP2/AUX2 measurement (pin 30)

110: BMON/AUX3 measurement (pin 31)

111: WIPER/AUX4 measurement (pin 12)

7Ah

AC-Link slot
selected by
SLT

11:0

ADCD

000h

Touchpanel ADC Data (read-only)

Bit 11 = MSB

Bit 0 = LSB

78h

WAIT

0: No effect (new ADC data overwrites
unread data in register 7Ah)

1: New data is held back, and
measurements delayed, until register 7Ah is
read)

Table 29 Touchpanel Digitiser Data

To avoid losing data that has not yet been read, the WM9712L can delay overwriting register 7Ah

with new data until the old data has been read. This function is enabled using the WAIT bit.

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If the SLEN bit is set to `1', then the touchpanel data appears on the AC-Link slot selected by the

SLT control bits, as shown below. The Slot 0 `tag' bit corresponding to the selected time slot is

asserted whenever there is new data on that slot.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

SLEN

Slot Readback Enable

0: Disabled (readback through register only)

1: Enable (readback slot selected by SLT)

76h

2:0

SLT

110

AC'97 Slot Selection for Touchpanel Data

000: Slot 5

001: Slot 6

...

101: Slot 10

110: Slot 11

111: RESERVED

Table 30 Returning Touchpanel Data Through an AC-Link Time Slot

TOUCHPANEL SETTLING TIME

For accurate touchpanel measurements, some settling time may be required between the switch

matrix applying a voltage across the touchpanel plate and the ADC sampling the signal. This time

delay function is built into the WM9712L and can be programmed as shown below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

76h

7:4

DEL

0000

(1 frame)

Touchpanel ADC Settling Time

Table 31 Touchpanel Settling Time Control (1)

DEL

DELAY

(AC-LINK FRAMES)

DELAY

(TIME)

0000

20.8

0001

41.7

0010

83.3

0011

167

0100

333

0101

667

0110

1ms

0111

1.33ms

1000

2ms

1001

128

2.67ms

1010

160

3.33ms

1011

192

4ms

1100

224

4.67ms

1101

256

5.33ms

1110

288

6ms

1111

No delay, switch matrix always on

Table 32 Touchpanel Settling Time Control (2)

The total time for co-ordinate or auxiliary measurements to complete is the delay time DEL, plus one

AC-Link frame (20.8

s). For a pressure measurement, the time taken is DEL plus two AC-Link

frames (41.6

s).

WM9712L

Production Data

PD Rev 4.0 December 2003

Setting DEL to `1111' reduces the settling time to zero, i.e. measurements begin immediately. This

mode is intended for fast sampling on AUX inputs. It is NOT intended for touchpanel digitisation.

There are several side-effects when DEL is set to `1111':

Co-ordinate mode does not work, i.e. the WM9712L behaves as if COO = 0, even if COO
= 1 (see "Measurement Types")

If X / Y co-ordinate or touch pressure measurements are selected (ADCSEL = 001, 010
or 011), then the switch matrix is constantly on, and current constantly flows in the
touchpanel. This increases power consumption in the system, and is therefore not
recommended for battery powered systems

In continuous mode (CTC = 1), setting DEL = 1111 increases the sampling rate of the
touchpanel ADC (see "Initiation of Measurements")

MASK INPUT CONTROL

Sources of glitch noise, such as the signals driving an LCD display, may feed through to the

touchscreen plates and affect measurement accuracy. In order to minimise this effect, a signal may

be applied to MASK (pin 47) to delay or synchronise the sampling of any input to the ADC. The effect

of the MASK signal depends on the the MSK[1-0] bits of register 78h, as described below.

MSK[1-0]

EFFECT OF SIGNAL ON MASK PIN

Mask has no effect on conversions GPIO input disabled (default)

Static; `hi' on MASK pin stops conversions, `lo' has no effect.

Edge triggered; rising or falling edge on MASK pin delays conversions

by an amount set in the DEL[3-0] register. Conversions are asynchronous to
the MASK signal.

Synchronous mode; conversions wait until rising or falling edge on MASK
initiates cycle; screen starts to be driven when the edge arrives, the
conversion sample being taken a period set by DEL[3-0] after the edge.

Table 33 Controlling the MASK Feature

Note that pin 47 can also be used as a GPIO(see "GPIO and Interrupt Control" section), or to output

the ADA signal (see below).

THE ADA SIGNAL

Whenever data becomes available from the touchpanel ADC, the internal ADA (ADC Data Available)

signal goes high and remains high until the data has been read from register 7Ah (if SLEN = 0) or

until it has been sent out on an AC-Link slot (if SLEN = 1).

ADA can be used to generate an interrupt, if the AW bit (register 52h, bit 12) is set (see "GPIO and

interrupt control" section)

It is also possible to output the ADA signal on pin 47, if this pin is not used as a GPIO. The GE4 bit

(register 56h, bit 12) must be set to `0' to achieve this (see "GPIO and interrupt control" section).

Alternatively, ADA can be read from bit 12 in register 54h.

Production Data

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AUXILIARY ADC INPUTS

The ADC used for touchpanel digitisation can also be used for auxiliary measurements, provided that

it is enabled (register 78h, PRP = 11). The WM9712L has four pins that can be used as auxiliary

ADC inputs:

COMP1 / AUX1 (pin 29)

COMP2 / AUX2 (pin 30)

BMON / AUX3 (pin 31)

WIPER / AUX4 (pin 12)

Note that pin 12 connects to the wiper of a 5-wire touchpanel wiper function. Auxiliary measurements

taken on pin 12 are only meaningful when it is not connected to a touchpanel (i.e. a 4-wire

touchpanel, or no touchpanel at all, is used). Pins 29 and 30 are also used as comparator inputs (see

Battery Alarm and Battery Measurement), but auxiliary measurements can still be taken on these

pins at any time. For the use of pin 31 see the "Battery Alarm And Battery Measurement" section,

note that the measured value from the BMON/AUX3 pin will be 1/3 of the actual value due to the

potential divider on this pin. The ADCSEL control bits select between different ADC inputs, as shown

below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

76h

Touchpanel
Digitiser
Control

14:12

ADCSEL

000

Touchpanel ADC Input Selector

000: No measurement

001-011: Touchpanel measurement (please
refer to Touchpanel Digitiser section)

100: COMP1 / AUX1 measurement (pin 29)

101: COMP2 AUX2 measurement (pin 30)

110: BMON / AUX3 measurement (pin 31)

111: WIPER / AUX 4 measurement (pin 12)

Table 34 Auxiliary ADC Measurements

Auxiliary ADC measurements are initiated in the same way as touchpanel measurements, and the

data is returned in the same manner. Please refer to the "Controlling the Touchpanel Interface"

section.

BATTERY MEASUREMENT USING THE BMON/AUX3 PIN

BMON/AUX3 (pin 31) has the capability to take inputs up to 5 volts (Assuming AVDD=3.3V) by

dividing down the input signal. The internal potential divider has a total resistance of 30k

. However,

it is only connected to the pin when an AUX3 measurement is requested, and remains connected for

the duration of one AC-Link frame (20.83

s, assuming a 24.576MHz clock crystal is used). The

effective input impedance of BMON/AUX3 is therefore given by:

BMON

= 30k

48kHz / [BMON sampling rate]

For example, if BMON is sampled ten times per second, the effective input resistance is 30k

48kHz / 10Hz = 144M

WM9712L

Production Data

PD Rev 4.0 December 2003

BATTERY ALARM AND ANALOGUE COMPARATORS

The battery alarm function differs from battery measurement in that it does not actually measure the

battery voltage. Battery alarm only indicates "OK", "Low" or "Dead". The advantage of the battery

alarm function is that it does not require a clock and can therefore be used in low-power sleep or

standby modes.

AUX1/

COMP1

AUX2/

COMP2

+
-

-
+

REF

GPIO2/

IRQ

GPIO

PINS

DEAD

BAT

LOW

BAT

GPIO /

INTERRUPT

LOGIC

BATT

WM9712L

ALARM

VOLTAGE

REGULATOR

AVDD, DCVDD, ...

Figure 13 Battery Alarm Example Schematic

The typical schematic for a dual threshold battery alarm is shown above. This alarm has two

thresholds, "dead battery" (COMP1) and "low battery" (COMP2). R1, R2 and R3 set the threshold

voltages. Their values can be up to about 1M

in order to keep the battery current [I

ALARM

= V

BATT

(R1+R2+R3)] to a minimum (higher resistor values may affect the accuracy of the system as leakage

currents into the input pins become significant).

Dead battery alarm: COMP1 triggers when V

BATT

< VREF

(R1+R2+R3) / (R2+R3)

A dead battery alarm is the highest priority of interrupt in the system. It should immediately save all

unsaved data and shut down the system. The GP15, GS15 and GW15 bits must be set to generate

this interrupt.

Low battery alarm: COMP2 triggers when V

BATT

< VREF

(R1+R2+R3) / R3

A low battery alarm has a lower priority than a dead battery alarm. Since the threshold voltage is

higher than for a dead battery alarm, there is enough power left in the battery to give the user a

warning and/or shut down "gracefully". When V

BATT

gets close to the low battery threshold, spurious

alarms are filtered out by the COMP2 delay function.

The purpose of the capacitor C is to remove from the comparator inputs any high frequency noise or

glitches that may be present on the battery (for example, noise generated by a charge pump). It

forms a low pass filter with R1, R2 and R3.

Low pass cutoff f

[Hz] = 1/ (2

(R1 || (R2+R3)))

Provided that the cutoff frequency is several orders of magnitude lower than the noise frequency f

this simple circuit can achieve excellent noise rejection.

Noise rejection [dB] = 20 log (f

/ f

)

The circuit shown above also allows for measuring the battery voltage V

BATT

. This is achieved simply

by setting the touchpanel ADC input to be either COMP1 (ADCSEL = 100) or COMP2 (ADCSEL =

101) (see also Auxiliary ADC Inputs).

Production Data

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The WM9712L has two on-chip comparators that can be used to implement a battery alarm function,

or other functions such as a window comparator. Each comparator has one of its inputs tied to any

one of three device pins and the other tied to a voltage reference. The voltage reference can be

either internally generated (VREF = AVDD/2) or externally connected on AUX4 (pin 12).

The comparator output signals are passed to the GPIO logic block (see "GPIO and Interrupt Control"

section), where they can be used to send an interrupt to the CPU via the AC-Link or via the IRQ pin,

and / or to wake up the WM9712L from sleep mode. COMP1/AUX1 (pin 29) corresponds to GPIO bit

15 and COMP2/AUX2 (pin30) to bit 14.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

CP1

COMP1 Polarity (see also "GPIO and Interrupt
Control")

0: Alarm when COMP1 voltage is above VREF

1: Alarm when COMP1 voltage is below VREF

4Eh

CP2

COMP2 Polarity (see also "GPIO and Interrupt
Control")

0: Alarm when COMP2 voltage is above VREF

1: Alarm when COMP2 voltage is below VREF

58h

15:13

COMP2
DEL

Low Battery Alarm Delay

000: No delay

001: 0.17s (2

= 8192 AC-Link frames)

010: 0.34s (2

= 16384 AC-Link frames)

011: 0.68s (2

= 32768 AC-Link frames)

100: 1.4s (2

= 65536 AC-Link frames)

101: 2.7s (2

= 131072 AC-Link frames)

110: 5.5s (2

= 262144 AC-Link frames)

111: 10.9s (2

= 524288 AC-Link frames)

Table 35 Comparator Control

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Comparator 1 Reference Voltage

VREF = AVDD/2

C1REF

WIPER/AUX4 (pin 12)

Comparator 1 Signal Source

AVDD/2 when C1REF='1'. Otherwise
comparator 1 is powered down

COMP1/AUX1 (pin 29)

COMP2/AUX2 (pin 30)

13:12

C1SRC

BMON/AUX3 (pin 31)

Comparator 2 Reference Voltage

VREF = AVDD/2

C2REF

WIPER/AUX4 (pin 12)

Comparator 2 Signal Source

AVDD/2 when C2REF='1'. Otherwise
comparator 2 is powered down

COMP1/AUX1 (pin 29)

COMP2/AUX2 (pin 30)

5Ch

Additional
Analogue
Functions

10:9

C2SRC

BMON/AUX3 (pin 31)

Table 36 Comparator Reference and Source Control

WM9712L

Production Data

PD Rev 4.0 December 2003

COMP2 DELAY FUNCTION

COMP2 has an optional delay function for use when the input signal is noisy. When COMP2 triggers

and the delay is enabled (i.e. COMP2DEL is non-zero), then GPIO bit 14 does not change state

immediately, and no interrupt is generated. Instead, the WM9712L starts a delay timer and checks

COMP2 again after the delay time has passed. If COMP2 is still active, then the GPIO bit is set and

an interrupt may be generated (depending on the state of the GW14 bit). If COMP2 is no longer

active, the GPIO bit is not set, i.e. all register bits are as if COMP2 had never triggered.

Note: If COMP2 triggers while the WM9712L is in sleep mode, and the delay is enabled, then the

device starts the on-chip crystal oscillator in order to count the time delay.

COMP2

TRIGGERS

START TIMER

COMP2?

WAIT

time=COMP2DEL

SHUT DOWN

TIMER

Inactive

Active

SET GI14

END

[FALSE ALARM]

COMP2

DEL?

non-zero

C2W?

END

000

Figure 14 COMP2 Delay Flow Chart

Production Data

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GPIO AND INTERRUPT CONTROL

The WM9712L has five GPIO pins that operate as defined in the AC'97 Revision 2.2 specification.

Each GPIO pin can be set up as an input or as an output, and has corresponding bits in register 54h

and in slot 12. The state of a GPIO output is determined by sending data through slot 12 of outgoing

frames (SDATAOUT). Data can be returned from a GPIO input by reading the register bit, or

examining slot 12 of incoming frames (SDATAIN). GPIO inputs can be made sticky, and can be

programmed to generate and interrupt, transmitted either through the AC-Link or through a

dedicated, level-mode interrupt pin (GPIO2/IRQ, pin 45).

GPIO pins 2 to 5 are multi-purpose pins that can also be used for other (non-GPIO) purposes, e.g.

as a SPDIF output or to signal pen-down. This is controlled by register 56h.

Independently of the GPIO pins, the WM9712L also has five virtual GPIOs. These are signals from

inside the WM9712L, which are treated as if they were GPIO input signals. From a software

perspective, virtual GPIOs are the same as GPIO pins, but they cannot be set up as outputs, and are

not tied to an actual pin. This allows for simple, uniform processing of different types of signals that

may generate interrupts (e.g. pen down, battery warnings, jack insertion, high-temperature warning,

or GPIO signals).

Figure 15 GPIO logic

WM9712L

Production Data

PD Rev 4.0 December 2003

GPIO

BIT

SLOT12

BIT

TYPE

PIN NO.

DESCRIPTION

GPIO Pin

GPIO1

GPIO Pin

GPIO2 / IRQ

enabled only when pin not used as IRQ

GPIO Pin

GPIO3 / PENDOWN

enabled only when pin not used as PENDOWN

GPIO Pin

GPIO4 / ADA / MASK

enabled only when pin not used as ADA

GPIO Pin

GPIO5 / SPDIF_OUT

enabled only when pin not used as
SPDIF_OUT

6-10

N/A

Unused

GPIO Logic not implemented for these bits

Virtual

GPIO

[Thermal Cutout]

Internal thermal cutout signal, indicates when
internal temperature reaches approximately
150

C (see "Thermal Sensor")

virtual

GPIO

[ADA]

Internal ADA (ADC Data Available) Signal

enabled only when auxiliary ADC is active

Virtual

GPIO

[PEN DOWN]

Internal PENDOWN Signal

enabled only when pen-down detection is
active

Virtual

GPIO

[COMP2]

Internal COMP2 output (Low Battery Alarm)

enabled only when COMP2 is on

Virtual

GPIO

[COMP1]

Internal COMP1 output (Dead Battery Alarm)

enabled only when COMP1 is on

Table 37 GPIO Bits and Pins

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The properties of the GPIOs are controlled through registers 4Ch to 52h, as shown below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

4Ch

GCn

GPIO Pin Configuration

0: Output

1: Input

GC11-15 are always `1'

Unused bits GC6-GC10 are always `0'

4Eh

GPn

GPIO Pin Polarity / Type

0: Active Low

1: Active High

[GIn = pin level XNOR GPn]

Unused bits GP6-GP10 are always `1'

50h

GSn

GPIO Pin Sticky

1: Sticky

0: Not Sticky

Unused bits GS6-GS10 are always `0'

52h

GWn

GPIO Pin Wake-up

1: Wake Up (generate interrupts from this pin)

0: No wake-up (no interrupts generated)

Unused bits GW6-GW10 are always `0'

54h

GIn

N/A

GPIO Pin Status

Read: Returns status of each GPIO pin

Write: Writing `0' clears sticky bit

Unused bits GI6-GI10 are always `0'

Table 38 GPIO Control

The following procedure is recommended for handling interrupts:

When the controller receives an interrupt, check register 54h. For each GPIO bit in descending order

of priority, check if the bit is `1'. If yes, execute corresponding interrupt routine, then write `0' to

corresponding bit in 54h. If no, continue to next lower priority GPIO. After all GPIOs have been

checked, check if the interrupt still present or no. If yes, repeat procedure. If no, then jump back to

process that ran before the interrupt.

If the system CPU cannot execute such an interrupt routine, it may be preferable to switch internal

signals (such as PENDOWN) directly onto the GPIO pins. However, in this case the interrupt signals

cannot be made sticky, and more GPIO pins are tied up both on the WM9712L and on the CPU.

WM9712L

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REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

GE2

GPIO2 / IRQ output select

0: Pin 45 disconnected from GPIO logic

set 4Ch, bit 2 to `0' to output IRQ signal

1: Pin 45 connected to GPIO logic (IRQ disabled)

GE3

GPIO3 / PENDOWN output select

0: Pin 46 disconnected from GPIO logic

set 4Ch, bit 3 to `0' to output PENDOWN signal

1: Pin 46 connected to GPIO logic

GE4

GPIO4 / ADA / MASK output select

0: Pin 47 disconnected from GPIO logic

set 4Ch, bit 4 to `0' to output ADA signal

set 4Ch, bit 4 to `1' to input MASK signal

1: Pin 47 connected to GPIO logic

56h

GPIO pins
function
select

GE5

GPIO5 / SPDIF output select

0: Pin 48 = SPDIF (disconnected from GPIO logic)

set 4Ch, bit 5 to `0' to output SPDIF signal

1: Pin 48 connected to GPIO logic (SPDIF
disabled)

Table 39 Using GPIO Pins for Non-GPIO Functions

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

IRQ INV

Inverts the IRQ signal (pin 45)

0: IRQ signal not inverted

1: IRQ signal inverted

58h

Additional
Functional
Control

WAKEEN

Enables GPIO wake-up

0: Disabled

1: Enabled

Table 40 Additional Functionality for GPIO Pins

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POWER MANAGEMENT

The WM9712L includes the standard power down control register defined by the AC'97 specification

(register 26h). Additionally, it also allows more specific control over the individual blocks of the device

through register 24h. Each particular circuit block is active when both the relevant bit in register 26h

AND the relevant bit in register 24h are set to `0'.

DEFAULT

REGISTER

ADDRESS

BIT

LABEL

NORMAL

PIN 47 `HI'

DURING

RESET

DESCRIPTION

PR6

0 (ON)

1 (OFF)

Disables HPOUTL, HPOUTR and
OUT3 Buffer

PR5

0 (ON)

1 (OFF)

Disables internal clock

PR4

0 (ON)

1 (OFF)

Disables AC-link interface
(external clock off)

PR3

0 (ON)

1 (OFF)

Disables VREF, analogue mixers
and outputs

PR2

0 (ON)

1 (OFF)

Disables analogue mixers,
LOUT2, ROUT2 (but not VREF)

PR1

0 (ON)

1 (OFF)

Disables stereo DAC

PR0

0 (ON)

1 (OFF)

Disables audio ADCs and input
Mux

REF

Read-only bit, indicates VREF is
ready (inverse of PR2)

ANL

Read-only bit, indicates analogue
mixers are ready (inverse of PR3)

DAC

Read-only bit, indicates audio
DACs are ready (inverse of PR1)

26h

Powerdown/
Status
register

ADC

Read-only bit, indicates audio
ADCs are ready (inverse of PR0)

Table 41 Powerdown and Status Register (Conforms to AC'97 Rev 2.2)

As can be seen from the table above, most blocks are `ON' by default. However, if pin 47

(GPIO4/ADA/MASK) is held high during reset, the WM9712L starts up with all blocks powered down

by default, saving power. This is achieved by connecting a pull-up resistor (e.g. 100k

) from pin 47

to DBVDD. Note that the state of pin 47 during reset only affects register 26h.

WM9712L

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PD Rev 4.0 December 2003

Table 42 Extended Power Down Register (Additional to AC'97 Rev 2.2)

Note:

*When disabling a PGA, always ensure that it is muted first.

ADDITIONAL POWER MANAGEMENT:

AUXDAC: see "Auxiliary DAC" section. AUXDAC is OFF by default.

Touchpanel Interface: see "Controlling the Touchpanel Digitiser / Power Management".
The touchpanel digitiser is OFF by default.

SLEEP MODE

Whenever the PR4 bit (reg. 26h) is set, the AC-Link interface is disabled, and the WM9712L is in

sleep mode. There is in fact a very large number of different sleep modes, depending on the other

control bits. For example, the low-power standby mode described below is a sleep mode. It is

desirable to use sleep modes whenever possible, as this will save power. The following functions do

not require a clock and can therefore operate in sleep mode:

Analogue-to-analogue audio (DACs and ADCs unused), e.g. phone call mode

Pen-down detection

GPIO and interrupts

Battery alarm / analogue comparators (but not battery measurement)

The WM9712L can awake from sleep mode as a result of

A warm reset on the AC-Link (according to the AC'97 specification)

A signal on a GPIO pin (if the pin is configured as an input, with wake-up enabled see
"GPIO and Interrupt Control" section)

A virtual GPIO event such as pen-down, battery alarm, etc. (see "GPIO and Interrupt
Control" section)

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

PD15

0 (ON)

Disables Crystal Oscillator

PD14

0 (ON)

Disables left audio DAC

PD13

0 (ON)

Disables right audio DAC

PD12

0 (ON)

Disables left audio ADC

PD11

0 (ON)

Disables right audio ADC

PD10

0 (ON)

Disables MICBIAS

PD9

0 (ON)

Disables left headphone mixer

PD8

0 (ON)

Disables right headphone mixer

PD7

0 (ON)

Disables speaker mixer

PD6

0 (ON)

Disables MONO_OUT buffer (pin 33) and phone
mixer

PD5

0 (ON)

Disables OUT3 buffer (pin 37)

PD4

0 (ON)

Disables headphone buffers (HPOUTL/R)

PD3

0 (ON)

Disables speaker outputs (LOUT2, ROUT2)

PD2

0 (ON)

Disables Line Input PGA (left and right) *

PD1

0 (ON)

Disables Phone Input PGA *

24h

Additional
power down
control

PD0

0 (ON)

Disables Mic Input PGA (left and right) *

Note: When analogue inputs or outputs are disabled, they are internally connected to VREF
through a large resistor (VREF=AVDD/2 except in OFF mode, when VREF itself is disabled). This
maintains the potential at that node and helps to eliminate pops when the pins are re-enabled.

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LOW POWER STANDBY MODE

If all the bits in registers 26h and 24h are set, then the WM9712L is in low-power standby mode and

consumes very little current. A 1M

resistor string remains connected across AVDD to generate

VREF. This is necessary if the on-chip analogue comparators are used (see "Battery Alarm and

Battery Measurement" section), and helps shorten the delay between wake-up and playback

readiness. If VREF is not required, the 1M

resistor string can be disabled by setting the SVD bit,

reducing current consumption further.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

58h

SVD

VREF Disable

0: VREF enabled using 1M

string (low-power

standby mode)

1 : VREF disabled, 1M

string disconnected

(OFF mode)

Table 43 Disabling VREF (for lowest possible power consumption)

SAVING POWER AT LOW SUPPLY VOLTAGES

The analogue supplies to the WM9712L can run from 1.8V to 3.6V. By default, all analogue circuitry

on the IC is optimized to run at 3.3V. This set-up is also good for all other supply voltages down to

1.8V. However, at lower voltages, it is possible to save power by reducing the internal bias currents

used in the analogue circuitry. This is controlled as shown below.

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

5Ch

6:5

VBIAS

Analogue Bias optimization

11 : Lowest bias current, optimized for 1.8V

10 : Low bias current, optimized for 2.5V

01, 00 : Default bias current, optimized for 3.3V

Table 44 Analogue Bias Selection

WM9712L

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AC97 DATA AND CONTROL INTERFACE

INTERFACE PROTOCOL

The WM9712Lhas a single AC'97 interface for both data transfer and control. The AC-Link uses 5

wires:

SDATAIN (pin 8) carries data from the WM9712L to the controller

SDATAOUT (pin 5) carries data from the controller to the WM9712L

BITCLK (pin 6) is a clock, normally generated by the WM9712L crystal oscillator and
supplied to the controller. However, BITCLK can also be passed to the WM9712L from
an off-chip generator.

SYNC is a synchronization signal generated by the controller and passed to the
WM9712L

RESETB resets the WM9712L to its default state

CONTROLLER

e.g. CPU

WM9712L

RESETB

SDATAIN

SDATAOUT

BITCLK

SYNC

24.576MHz
XTAL

AC-LINK

ANALOGUE

INPUTS /

OUTPUTS

Figure 16 AC-Link Interface (typical case with BITCLK generated by the AC97 codec)

The SDATAIN and SDATAOUT signals each carry 13 time-division multiplexed data streams (slots 0

to 12). A complete sequence of slots 0 to 12 is referred to as an AC-Link frame, and contains a total

of 256 bits. The frame rate is 48kHz. This makes it possible to simultaneously transmit and receive

multiple data streams (e.g. audio, touchpanel, AUXDAC, control) at sample rates up to 48kHz.

Detailed information can be found in the AC'97 (Revision 2.2) specification, which can be obtained at

www.intel.com/labs/media/audio/

Note:

SDATAOUT and SYNC must be held low for when RESETB is applied. These signals must be held

low for the entire duration of the RESETB pulse and especially during the low-to-high transition of

RESETB. If either is set high during reset the AC'97 device may enter test modes. Information

relating to this operation is available in the AC'97 specification or in Wolfson applications note WAN-

0104 available at www.wolfsonmirco.com.

Production Data

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INTERFACE TIMING

Test Characteristics:

DBVDD = 3.3V, DCVDD = 3.3V, DGND1 = DGND2 = 0V, T

= -25

C to +85

C, unless otherwise stated.

CLOCK SPECIFICATIONS

BITCLK

SYNC

CLK_HIGH

CLK_LOW

CLK_PERIOD

SYNC_HIGH

SYNC_LOW

SYNC_PERIOD

Figure 17 Clock Specifications (50pF External Load)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNIT

BITCLK frequency

12.288

MHz

BITCLK period

CLK_PERIOD

81.4

BITCLK output jitter

750

BITCLK high pulse width (Note 1)

CLK_HIGH

40.7

BITCLK low pulse width (Note 1)

CLK_LOW

40.7

SYNC frequency

kHz

SYNC period

SYNC_PERIOD

20.8

SYNC high pulse width

SYNC_HIGH

1.3

SYNC low pulse width

SYNC_LOW

19.5

Note:

1. Worst case duty cycle restricted to 45/55

DATA SETUP AND HOLD

Figure 18 Data Setup and Hold (50pF External Load)

Note:

Setup and hold times for SDATAIN are with respect to the AC'97 controller, not the
WM9712L.

WM9712L

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PD Rev 4.0 December 2003

PARAMETER

SYMBOL

MIN

TYP

MAX

UNIT

Setup to falling edge of BITCLK

SETUP

Hold from falling edge of BITCLK

HOLD

SIGNAL RISE AND FALL TIMES

BITCLK

SYNC

SDATAIN

SDATAOUT

trise

CLK

tfall

CLK

trise

SYNC

tfall

SYNC

trise

DIN

tfall

DIN

trise

DOUT

tfall

DOUT

Figure 19 Signal Rise and Fall Times (50pF External Load)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNIT

BITCLK rise time

trise

CLK

BITCLK fall time

tfall

CLK

SYNC rise time

trise

SYNC

SYNC fall time

tfall

SYNC

SDATAIN rise time

trise

DIN

SDATAIN fall time

tfall

DIN

SDATAOUT rise time

trise

DOUT

SDATAOUT fall time

tfall

DOUT

AC-LINK POWERDOWN

SYNC

BITCLK

SDATAOUT

WRITE

TO 0X20

DATA PR4

DON'T
CARE

SDATAIN

SLOT 1

SLOT 2

S2_PDOWN

Figure 20 AC-Link Powerdown Timing

AC-Link powerdown occurs when PR4 (register 26h, bit 12) is set (see "Power Management"

section).

PARAMETER

SYMBOL

MIN

TYP

MAX

UNIT

End of Slot 2 to BITCLK and SDATAIN
low

S2_PDOWN

1.0

WM9712L

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PD Rev 4.0 December 2003

REGISTER MAP

Note: Highlighted bits differ from the AC'97 specification (newly added for non-AC'97 function, or same bit used in a
different way, or for another function)

Reg

Name

Default

00hReset

SE4

SE3

SE2

SE1

SE0

ID9

ID8

ID7

ID6

ID5

ID4

ID3

ID2

ID1

ID0

6174h

02hLOUT2/ROUT2 Volume

INV

8000h

04hHeadph

one Volume

8000h

06hMONOOUT Volume

8000h

08hDAC Tone Control

DAT

0F0Fh

0AhPCBEEP Input

B2H

B2S

B2P

AAA0h

0ChPHONE Volume

P2H

P2S

C008h

0EhMIC Volume

M12P

M22P

20dB

6808h

10hLINEIN Volume

L2H

L2S

L2P

E808h

12hAUXDAC Volume / Routing

A2H

A2S

A2P

AXE

AAA0h

14hSidetone Volume

STM

AD00h

16hOUT3 Volume

SRC

8000h

18hDAC Volume

D2H

D2S

D2P

E808h

1AhRecord Select

BOOST

R2P

BST

3000h

1ChRecord Gain

RMU

GRL

GRR

8000h

20hGeneral Purpose

3DE

0000h

22hDAC 3D Control

3DLC

3DUC

0000h

24hPowerdown

PD15

PD14

PD13

PD12

PD11

PD10

PD9

PD8

PD7

PD6

PD5

PD4

PD3

PD2

PD1

PD0

0000h

26hPowerdown Ctrl/Stat

PR6

PR5

PR4

PR3

PR2

PR1

PR0

REF

ANL

DAC

ADC

000Fh

FF00h

28hExtended Audio ID

ID1

ID0

REV1

REV0

AMAP

LDAC

SDAC

CDAC

VRM

SPDIF

DRA

VRA

0405h

2AhExt'd Audio stst/ctrl

SPCV

SEN

VRA

0410h

2ChAudio DACs Sample Rate

BB80h

2EhAUXDAC Sample Rate

BB80h

32hAudio ADCs Sample Rate

BB80h

3AhSPDIF control

DRS

PRE

COPY AUD IB

PRO

2000h

4ChGPIO Pin Configuration

GC5

GC4

GC3

GC2

GC1

F83Eh

4EhGPIO Pin Polarity / Type

C1P

C2P

GP5

GP4

GP3

GP2

GP1

FFFFh

50hGPIO Pin Sticky

C1S

C2S

GS5

GS4

GS3

GS2

GS1

0000h

52hGPIO Pin Wake-Up

C1W

C2W

GW5

GW4

GW3

GW2

GW1

0000h

54hGPIO Pin Status

C1I

C2I

GI5

GI4

GI3

GI2

GI1

GPIO pins

56hGPIO Pin Sh

aring

GE5

GE4

GE3

GE2

F83Eh

58hAdditional Functions (1)

JIEN

FRC

SVD

WAKE

IRQ

INV

0008h

5AhVendor Reserved

5ChAdd. Functions (2)

AMUTE

C1 REF

C2 REF

AMEN

ADCO

HPF

ENT

0000h

5EhVendor Reserved

60hALC Control

B032h

62hALC / Noise Gate Control

ALC

NG AT

NGG

3E00h

64hAUXDAC input control

XSLE

0000h

66h-

74h

Vendor Reserved

76hDigitiser Reg 1

POLL

COO

CTC

SLEN

0006h

78hDigitiser Reg 2

RPR

45W

PDEN

WAIT

PIL

0001h

7AhDigitiser Read Back

PNDN

0000h

7ChVendor ID1

574Dh

7EhVendor ID2

4C12h

RESERVED FOR TEST

RESERVED. DO NOT WRITE TO THESE REGISTERS

OUT3 Volume

LOUT2 Volume

ROUT2 Volume

STVOL

LINEINLVOL

LINEINRVOL

A2HVOL

A2SVOL

B2HVOL

COMP2DEL

B2SVOL

SPSR

CC (Category Code)

ADCSR (Audio ADCs Sample Rate)

(Extended)

RECVOLL

RECVOLR

ASCII character "L"

"12" (indicates part number WM9712)

NGTH (threshold)

AUXDAC VAL

ASCII character "W"

ASCII character "M"

ALCSEL

SLT

ADCD (TOUCHPANEL ADC DATA)

Die Revision

3DDEPTH

DACSR (Audio DACs Sample Rate)

AUXDACSR (Auxiliary DAC Sample Rate)

SPSA

Default for reg. 26h - pin 47 "low" or unconnected during reset

Default for reg. 26h - pin 47 "high" during reset (recommended for lowest power)

(Extended)

HPOUTR Volume

HPOUTL Volume

RECSL

RECSR

Left DAC Volume

Right DAC Volume

R2P

ALCM

ALCVOL

OUT3SRC

A2PVOL

MONOOUT Volume

BASS

TRBL

MICVOL (Mono /Right)

B2PVOL

PHONEIN Volume

LMICVOL (Left Only)

C2SRC

AUXDACSLT

RPU

MSK

DEL

ASS

C1SRC

VBIAS

ALCL (target level)

HLD (hold time)

ADCSRC

PRP

RESERVED FOR TEST

MAXGAIN

ZC TIMEOUT

ADCSEL

DCY (decay time)

ATK (attack time)

Table 45 WM9712L Register Map

Production Data

WM9712L

PD Rev 4.0 December 2003

REGISTER BITS BY ADDRESS

Register 00h is a read-only register. Writing any value to this register resets all registers to their default, but does not
change the contents of reg. 00h. Reading the register reveals information about the codec to the driver, as required by the
AC'97 Specification, Revision 2.2

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

14:10

SE [4:0]

11000

Indicates a codec from Wolfson Microelectronics

9:6

ID9:6

0101

Indicates 18 bits resolution for ADCs and DACs

ID5

Indicates that the WM9712L supports bass boost

ID4

Indicates that the WM9712L has a headphone output

ID3

Indicates that the WM9712L does not support simulated stereo

ID2

Indicates that the WM9712L supports bass and treble control

ID1

Indicates that the WM9712L does not support modem functions

00h

ID0

Indicates that the WM9712L does not have a dedicated microphone
ADC

Intel's AC'97
Component
Specification,
Revision 2.2,
page 50

Register 02h controls the output pins LOUT2 and ROUT2.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

1 (mute)

Mutes LOUT2 and ROUT2.

13:8

LOUT2 VOL

000000 (0dB)

LOUT2 volume

0 (OFF)

Enables zero-cross detector

INV

0 (not inverted)

Inverts LOUT2 (for BTL speaker operation)

02h

5:0

ROUT2 VOL

000000 (0dB)

ROUT2 volume

Analogue
Audio Outputs

Register 04h controls the headphone output pins, HPOUTL and HPOUTR.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

1 (mute)

Mutes HPOUTL and HPOUTR.

13:8

HPOUTL VOL

000000 (0dB)

HPOUTL volume

0 (OFF)

Enables zero-cross detector

04h

5:0

HPOUTR VOL

000000 (0dB)

HPOUTR volume

Analogue
Audio Outputs

Register 06h controls the analogue output pin MONOOUT.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

1 (mute)

Mutes MONOOUT.

0 (OFF)

Enables zero-cross detector

06h

5:0

MONOOUT
VOL

000000 (0dB)

MONOOUT volume

Analogue
Audio Outputs

WM9712L

Production Data

PD Rev 4.0 December 2003

Register 08h controls the bass and treble response of the left and right audio DAC (but not AUXDAC).

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

0 (linear)

Selects linear bass control or adaptive bass boost

0 (low)

Selects bass cut-off frequency

11:8

BASS

1111 (OFF)

Controls bass intensity

DAT

0 (OFF)

Enables 6dB pre-DAC attenuation

0 (high)

Selects treble cut-off frequency

08h

3:0

TRBL

1111 (OFF)

Controls treble intensity

Audio DACs,
Tone Control /
Bass Boost

Register 0Ah controls the analogue input pin PCBEEP.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

B2H

1 (mute)

Mutes PCBEEP to headphone mixer path

14:12

B2HVOL

010 (0dB)

Controls gain of PCBEEP to headphone mixer path

B2S

1 (mute)

Mutes PCBEEP to speaker mixer path

10:8

B2SVOL

010 (0dB)

Controls gain of PCBEEP to speaker mixer path

B2P

1 (mute)

Mutes PCBEEP to phone mixer path

0Ah

6:4

B2PVOL

010 (0dB)

Controls gain of PCBEEP to phone mixer path

Analogue
Inputs,
PCBEEP Input

Register 0Ch controls the analogue input pin PHONE.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

P2H

1 (mute)

Mutes PHONE to headphone mixer path

P2S

1 (mute)

Mutes PHONE to speaker mixer path

0Ch

4:0

PHONEVOL

01000 (0dB)

Controls PHONE input gain to all mixers (but not to ADC)

Analogue
Inputs,
PHONE Input

Register 0Eh controls the analogue input pins MIC1 and MIC2.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

M12P

1 (mute)

Mutes MIC1 to phone mixer path

M22P

1 (mute)

Mutes MIC2 to phone mixer path

12:8

LMICVOL

01000 (0dB)

Controls volume of MIC1 (left), in stereo mode only

20dB

0 (OFF)

Enables 20dB gain boost

6:5

00 (MIC1 only)

Selects microphone mode. 00=MIC1 only, 01=differential,
10=MIC2 only, 11=stereo

0Eh

4:0

MICVOL

01000 (0dB)

Controls mic volume (except MIC1 in stereo mode)

Analogue
Inputs,
Microphone
Input

Register 10h controls the analogue input pins LINEINL and LINEINR.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

L2H

1 (mute)

Mutes LINEIN to headphone mixer path

L2S

1 (mute)

Mutes LINEIN to speaker mixer path

L2P

1 (mute)

Mutes LINEIN to phone mixer path

12:8

LINEINLVOL

01000 (0dB)

Controls LINEINL input gain to all mixers (but not to ADC)

10h

4:0

LINEINRVOL

01000 (0dB)

Controls LINEINR input gain to all mixers (but not to ADC)

Analogue
Inputs, Line
Input

Production Data

WM9712L

PD Rev 4.0 December 2003

Register 12h controls the output signal of the auxiliary DAC.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

A2H

1 (mute)

Mutes AUXDAC to headphone mixer path

14:12

A2HVOL

010 (0dB)

Controls gain of AUXDAC to headphone mixer path

A2S

1 (mute)

Mutes AUXDAC to speaker mixer path

10:8

A2SVOL

010 (0dB)

Controls gain of AUXDAC to speaker mixer path

A2P

1 (mute)

Mutes AUXDAC to phone mixer path

6:4

A2PVOL

010 (0dB)

Controls gain of AUXDAC to phone mixer path

12h

AXE

0 (0FF)

Enables AUXDAC

Auxiliary DAC

Register 14h controls the side tone paths.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

STM

1 (mute)

Mutes microphone to headphone mixer path

14:12

STVOL

010 (0dB)

Controls gain of microphone to headphone mixer path

11:10

ALCM

11 (mute both)

Selects ALC to headphone mixer path. 00=stereo,
01=right only, 10=left only, 11=mute both left and right

14h

9:7

ALCVOL

010 (0dB)

Controls gain of ALC to headphone mixer path

Audio Mixers,
Side Tone
Control

Register 16h controls the analogue output pin OUT3, and also contains one control bit that affects LOUT2 and ROUT2.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

1 (mute)

Mutes OUT3.

10:9

OUT3SRC

00 (-HPOUTL)

Selects source of OUT3 signal. 00=-HPOUTL, 01=VREF,
10=HPOUTL+HPOUTR, 11=-MONOOUT

SRC

0 (spkr mix)

Selects source of LOUT2 and ROUT2 signals. 0=from
speaker mixer, 1=from headphone mixer

0 (disabled)

Zero-cross enable

16h

5:0

OUT3VOL

000000 (0dB)

OUT3 volume

Analogue
Audio Outputs

Register 18h controls the audio DACs (but not AUXDAC).

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

D2H

1 (mute)

Mutes DAC to headphone mixer path

D2S

1 (mute)

Mutes DAC to speaker mixer path

D2P

1 (mute)

Mutes DAC to phone mixer path

12:8

LDACVOL

01000 (0dB)

Controls left DAC input gain to all mixers

18h

4:0

RDACVOL

01000 (0dB)

Controls right DAC input gain to all mixers

Audio DACs

Register 1Ah controls the record selector and the ADC to phone mixer path.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

BOOST

0 (OFF)

Enables 20dB gain boost for recording

13:12

R2P

11 (mute)

Controls ADC to phone mixer path. 00=stereo, 01=left
ADC only, 10=right ADC only, 11=mute left and right

R2PBST

0 (OFF)

Enables 20dB gain boost for ADC to phone mixer path

10:8

RECSL

000 (mic)

Selects left ADC signal source

1Ah

2:0

RECSR

000 (mic)

Selects right ADC signal source

Audio ADC,
Record
Selector

WM9712L

Production Data

PD Rev 4.0 December 2003

Register 1Ch controls the.recording gain.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

RMU

1 (mute)

Mutes audio ADC input

GRL

0 (standard)

Selects gain range for PGA of left ADC. 0=0...+22.5dB in
1.5dB steps, 1=-17.25...+30dB in 0.75dB steps

13:8

RECVOLL

000000 (0dB)

Controls left ADC recording volume

0 (OFF)

Enables zero-cross detector

GRR

0 (standard)

Selects gain range for PGA of left ADC. 0=0...+22.5dB in
1.5dB steps, 1=-17.25...+30dB in 0.75dB steps

1Ch

5:0

RECVOLR

000000 (0dB)

Controls right ADC recording volume

Audio ADC,
Record Gain

Register 20h is a "general purpose" register as defined by the AC'97 specification. Only two bits are implemented in the
WM9712L.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

3DE

0 (OFF)

Enables 3D enhancement

Audio DACs, 3D Stereo
Enhancement

20h

0 (OFF)

Enables loopback (i.e. feed ADC output data
directly into DAC)

Intel's AC'97 Component
Specification, Revision 2.2, page 55

Register 22h controls 3D stereo enhancement for the audio DACs.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

3DLC

0 (low)

Selects lower cut-off frequency

3DUC

0 (high)

Selects upper cut-off frequency

22h

3:0

3DDEPTH

0000 (0%)

Controls depth of 3D effect

Audio DACs,
3D Stereo
Enhancement

Register 24h is for power management additional to the AC'97 specification. Note that the actual state of each circuit block
depends on both register 24h AND register 26h.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

PD15

0 *

Disables Crystal Oscillator

PD14

0 *

Disables left audio DAC

PD13

0 *

Disables right audio DAC

PD12

0 *

Disables left audio ADC

PD11

0 *

Disables right audio ADC

PD10

0 *

Disables MICBIAS

PD9

0 *

Disables left headphone mixer

PD8

0 *

Disables right headphone mixer

PD7

0 *

Disables speaker mixer

PD6

0 *

Disables MONO_OUT buffer (pin 33) and phone mixer

PD5

0 *

Disables OUT3 buffer (pin 37)

PD4

0 *

Disables headphone buffers (HPOUTL/R)

PD3

0 *

Disables speaker outputs (LOUT2, ROUT2)

PD2

0 *

Disables Line Input PGA (left and right)

PD1

0 *

Disables Phone Input PGA

24h

PD0

0 *

Disables Mic Input PGA (left and right)

Power
Management

* "0" corresponds to "ON", if and only if the corresponding bit in register 26h is also 0.

Production Data

WM9712L

PD Rev 4.0 December 2003

Register 26h is for power management according to the AC'97 specification. Note that the actual state of many circuit
blocks depends on both register 24h AND register 26h.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

PR6

Disables HPOUTL, HPOUTR and OUT3 Buffer

PR5

Disables Internal Clock

PR4

Disables AC-link interface (external clock off)

PR3

Disables VREF, analogue mixers and outputs

PR2

Disables analogue mixers, LOUT2, ROUT2 (but not VREF)

PR1

Disables Stereo DAC and AUXDAC

PR0

see note

Disables audio ADCs and input Mux

REF

inverse of PR2

Read-only bit, Indicates VREF is ready

ANL

inverse of PR3

Read-only bit, indicates analogue mixers are ready

DAC

inverse of PR1

Read-only bit, indicates audio DACs are ready

ADC

inverse of PR0

Read-only bit, indicates audio ADCs are ready

Power
Management

Note: PR6 to PR0 default to 1 if pin 47 is held high during reset, otherwise they default to 0.

Register 28h is a read-only register that indicates to the driver which advanced AC'97 features the WM9712L supports.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

15:14

Indicates that the WM9712L is configured as the primary codec in
the system.

11:10

REV

Indicates that the WM9712L conforms to AC'97 Rev2.2

AMAP

Indicates that the WM9712L does not support slot mapping

LDAC

Indicates that the WM9712L does not have an LFE DAC

SDAC

Indicates that the WM9712L does not have Surround DACs

CDAC

Indicates that the WM9712L does not have a Centre DAC

VRM

Indicates that the WM9712L does not have a dedicated, variable
rate microphone ADC

SPDIF

Indicates that the WM9712L supports SPDIF output

DRA

Indicates that the WM9712L does not support double rate audio

28h

VRA

Indicates that the WM9712L supports variable rate audio

Intel's AC'97
Component
Specification,
Revision 2.2,
page 59

Register 2Ah controls the SPDIF output and variable rate audio.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

SPCV

1 (valid)

SPDIF validity bit (read-only)

5:4

SPSA

01 (slots 6, 9)

Controls SPDIF slot assignment. 00=slots 3 and 4,
01=6/9, 10=7/8, 11=10/11

SEN

0 (OFF)

Enables SPDIF output enable

2Ah

VRA

0 (OFF)

Enables variable rate audio

Digital Audio
(SPDIF)
Output

Registers 2Ch, 2Eh 32h and control the sample rates for the stereo DAC, auxiliary DAC and audio ADC, respectively.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

2Ch

all

DACSR

BB80h

Controls stereo DAC sample rate

2Eh

all

AUXDACSR

BB80h

Controls auxiliary DAC sample rate

32h

all

ADCSR

BB80h

Controls audio ADC sample rate

Variable Rate
Audio /
Sample Rate
Conversion

Note: The VRA bit in register 2Ah must be set first to obtain sample rates other than 48kHz

WM9712L

Production Data

PD Rev 4.0 December 2003

Register 3Ah controls the SPDIF output.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

Validity bit; `0' indicates frame valid, `1' indicates frame not
valid

DRS

Indicates that the WM9712L does not support double rate
SPDIF output (read-only)

13:12

SPSR

Indicates that the WM9712L only supports 48kHz
sampling on the SPDIF output (read-only)

Generation level; programmed as required by user

10:4

0000000

Category code; programmed as required by user

PRE

Pre-emphasis; `0' indicates no pre-emphasis, `1' indicates
50/15us pre-emphasis

COPY

AUDIB

Non-audio; `0' indicates data is PCM, `1' indicates non-
PCM format (e.g. DD or DTS)

3Ah

PRO

Professional; `0' indicates consumer, `1' indicates
professional

Digital Audio
(SPDIF)
Output

Register 4Ch to 54h control the GPIO pins and virtual GPIO signals.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

4Ch

all 1 (all inputs)
except unused
bits

Controls GPIO configuration as inputs or as outputs (note:
virtual GPIOs can only be inputs)

4Eh

all 1

Controls GPIO polarity (actual polarity depends on register
4Ch AND register 4Eh)

50h

all 0 (not sticky)

Makes GPIO signals sticky

52h

all 0 (OFF)

Enables wake-up for each GPIO signal

54h

= status of GPIO
inputs

GPIO pin status (read from inputs, write `0' to clear sticky bits)

Controls Comparator 1 signal (virtual GPIO)

Controls Comparator 2 signal (virtual GPIO)

Controls Pen-Down Detector signal (virtual GPIO)

Controls ADA signal (virtual GPIO)

Controls Thermal sensor signal (virtual GPIO)

10-6

Unused

Controls GPIO5 (pin 48)

Controls GPIO4 (pin 47)

Controls GPIO3 (pin 46)

Controls GPIO2 (pin 45)

please
refer to
the
register
map

Controls GPIO1 (pin 44)

GPIO and
Interrupt
Control

Register 56h controls the use of GPIO pins for non-GPIO functions.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

GE5

1 (GPIO)

Selects between GPIO5 and SPDIF_OUT function for pin 48

GE4

1 (GPIO)

Selects between GPIO4 and ADA/MASK functionS for pin 47

GE3

1 (GPIO)

Selects between GPIO3 and PENDOWN function for pin 46

56h

GE2

1 (GPIO)

Selects between GPIO2 and IRQ function for pin 45

GPIO and
Interrupt
Control

Production Data

WM9712L

PD Rev 4.0 December 2003

Register 58h controls several additional functions.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

15:13

COMP2DEL

000 (no delay)

Selects Comparator 2 delay

Battery Alarm

JIEN

Enables Jack Insert Detection

FRC

Forces Jack Insert Detection

Analogue Audio Outputs, Jack
Insertion and Auto-Switching

SVD

0 (enabled)

Disables VREF for lowest possible power
consumption

Power Management

3:2

DIE REV

Indicates device revision. 00=Rev.A, 01=Rev.B, 10=Rev.C

N/A

WAKEEN

0 (no wake-up)

Enables GPIO wake-up

58h

IRQ INV

0 (not inverted)

Inverts the IRQ signal (pin 45)

GPIO and Interrupt Control

Register 5Ch controls several additional functions.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

AMUTE

Read-only bit to indicate DAC auto-muting

Audio DACs, Stereo DACs

C1REF

0 (AVDD/2)

Selects Comparator 1 Reference Voltage

13:12

C1SRC

00 (OFF)

Selects Comparator 1 Signal Source

C2REF

0 (AVDD/2)

Selects Comparator 1 Reference Voltage

10:9

C2SRC

00 (OFF)

Selects Comparator 1 Signal Source

Battery Alarm

Selects differential microphone input pins. 0=MIC1
and MIC2, 1=LINEL and LINER

Analogue Inputs,
Microphone Input

AMEN

0 (OFF)

Enables DAC Auto-Mute

6:5

VBIAS

Selects analogue bias for lowest power, depending
on AVDD supply. 0X=3.3V, 10=2.5V, 11=1.8V

Power Management

ADCO

Selects source of SPDIF data. 0=from SDATAOUT,
1= from audio ADC

Digital Audio (SPDIF)
Output

HPF

Disables ADC high-pass filter

Audio ADC

ENT

Enables thermal sensor

Analogue Audio Outputs,
Thermal Sensor

5Ch

1:0

ASS

Selects time slots for stereo ADC data. 00=slots 3
and 4, 01=7/8, 10=6/9, 11=10/11

Audio ADC, ADC Slot
Mapping

Registers 60h and 62h control the ALC and Noise Gate functions.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

15:12

ALCL

1011 (-12dB)

Controls ALC threshold

11:8

HLD

0000 (0 ms)

Controls ALC hold time

7:4

DCY

0011 (192 ms)

Controls ALC decay time

60h

3:0

ATK

0010 (24 ms)

Controls ALC attack time

15:14

ALCSEL

00 (OFF)

Controls which channel ALC operates on. 00=none,
01=right only, 10=left only, 11=both

13:11

MAXGAIN

111 (+30dB)

Controls upper gain limit for ALC

10:9

ZC TIMEOUT

11 (slowest)

Controls time-out for zero-cross detection

ALCZC

0 (OFF)

Enables zero-cross detection for ALC

NGAT

0 (OFF)

Enables noise gate function

NGG

0 (hold gain)

Selects noise gate type. 0=hold gain, 1=mute

62h

4:0

NGTH

00000 (-76.5dB)

Controls noise gate threshold

Audio ADC,
Automatic
Level Control

WM9712L

Production Data

PD Rev 4.0 December 2003

Register 64h controls the input signal of the auxiliary DAC.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

XSLE

Selects input for AUXDAC. 0=from AUXDACVAL (for DC
signals), 1=from AC-Link slot (for AC signals)

14:12

AUXDACSLT

000 (Slot 5)

Selects input slot for AUXDAC (with XSLE=1)

64h

11:0

AUXDACVAL

000000000

AUXDAC Digital Input for AUXDAC (with XSLE=0). 000h=
minimum, FFFh=full-scale

Auxiliary DAC

Registers 76h, 78h and 7Ah control the touchpanel interface.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

POLL

Writing "1" starts a measurement (this bit resets itself)

14:12

ADCSEL

000 (none)

Selects measurement type

COO

0 (OFF)

Enables co-ordinate mode

CTC

0 (polling)

Enables continuous conversions

9:8

00 (93.75Hz)

Controls conversion rate in continuous mode

7:4

DEL

0000 (20.8

Controls touchpanel settling time

SLEN

Enables slot readback of touchpanel data

76h

2:0

SLT

Selects time slot for readback of touchpanel data

15:14

PRP

Selects mode of operation. 00=OFF, 01=pen detect with
wake-up, 10=pen detect without wake-up, 11=running

RPR

Selects wake-up mode. 0=AC-Link only, 1=AC-Link and
WM9712L auto-wake-up

45W

0 (4-wire)

Selects 4-wire or 5-wire touchpanel

PDEN

0 (always)

Selects when touchpanel measurements take place.
0=always, 1=only when pen is down

WAIT

Controls data readback from register 7Ah. 0=overwrite old
data with new, 1=wait until old data has been read

PIL

0 (200

Controls current used for pressure measurement. 1=400

7:6

MSK

00 (OFF)

Controls MASK feature

78h

5:0

RPU

000001 (64k

)

Controls internal pull-up resistor for pen-down detection

PNDN

0 (pen up)

Indicates pen status.

14:12

ADCSRC

000 (none)

Indicates measurement type

7Ah

read
only

11:0

ADCD

000h

Returns data from touchpanel / AUXADC

Touchpanel
Interface

Register 7Ch and 7Eh are read-only registers that indicate to the driver that the codec is a WM9712L.

REG

ADDR

BIT

LABEL

DEFAULT

DESCRIPTION

REFER TO

15:8

F7:0

57h

ASCII character "W" for Wolfson

7Ch

7:0

S7:0

4Dh

ASCII character "M"

15:8

T7:0

4Ch

ASCII character "L"

7Eh

7:0

REV7:0

12h

12 for WM9712L

Intel's AC'97
Component
Specification,
Revision 2.2,
page 50

Production Data

WM9712L

PD Rev 4.0 December 2003

APPLICATIONS INFORMATION

RECOMMENDED EXTERNAL COMPONENTS

1
9

25
38

DBVDD
DCVDD

AVDD

TPVDD

PCBEEP

PHONE

X+/BR

Y+/TR

X-/TL

Y-/BL

MIC1

MIC2

LINEINL

LINEINR

SDATAOUT

BITCLK

SDATAIN

SYNC

RESETB

AC-

LINK

XTLOUT

XTLIN

GND

4
7

DGND2

DGND1

AGND

AGND2

SPKGND

LOUT2

ROUT2

OUT3

HPOUTL

HPOUTR

GPIO1

GPIO2/IRQ

GPIO3/PENDOWN

GPIO4/ADA/MASK

GPIO5/SPDIF_OUT

MICBIAS

VREF

CAP2

WM9712L

AGND

C15

C27

C28

C12

C13

C14

C10

C16

C17

C18

C19

C20

C11

C25

C26

C22

C23

SPKVDD
HPVDD

GND

AGND

GND

HPGND

TPGND

COMP1/AUX1

WIPER/AUX4

BMON/AUX3

COMP2/AUX2

MONOOUT

C21

Layout

Notes:

1. C1 to C6, C9 C11 and C13 should be as close to
the relative WM9712L connecting pin as possible.
2. AGND and DGND should be connected as close
to the WM9712L as possible.

C24

DVDD

AVDD

See External Components

Descriptions for details

DVDD

GND

AGND

AVDD

DBVDD

Figure 23 External Components Diagram

WM9712L

Production Data

PD Rev 4.0 December 2003

COMPONENT

REFERENCE

SUGGESTED

VALUE

DESCRIPTION

C1 - C6

100nF

De-coupling for DBVDD,DCVDD,TPVDD,AVDD,SPKVDD,HPVDD

C7 - C8

10uF

Reservoir capacitor for DVDD, AVDD. Should the supplies use separate sources then
additional capacitors will be required of each additional source.

100nF

De-coupling for CAP2.

C10

10uF

Reservoir capacitor for CAP2

C11

100nF

De-coupling for VREF

C12

10uF

Reservoir capacitor for VREF

C13

100nF

De-coupling for MICBIAS - Not required if MICBIAS output is not used

C14

10uF

Reservoir capacitor for MICBIAS - Not required if MICBIAS output is not used

C27 & C28

22pF

Required when used with a parallel resonant crystal.

C15 - C20

1uF

AC coupling capacitors

C21 - C23

2.2uF

Output AC coupling capacitors to remove VREF DC level from outputs

C24 - C26

220

Output AC coupling capacitors to remove VREF DC level from outputs.

100k

Pull-up resistor, ensures that all circuit blocks are OFF by default

24.576MHz

AC'97 master clock frequency. A bias resistor is not required but if connected will not
affect operation if the value is large (above 1M

)

Table 46 External Components Descriptions

Note:

1. For Capacitors C7, C8, C10, C12 and C14 it is recommended that very low ESR components are used.

LINE OUTPUT

The headphone outputs, HPOUTL and HPOUTR, can be used as stereo line outputs. The speaker

outputs, LOUT2 and ROUT2, can also be used as line outputs, if LOUT2 is not inverted for BTL

operation (INV = 0). Recommended external components are shown below.

HPGND

LINE-OUT

SOCKET

(LEFT)

1uF

100 Ohm

HPOUTL /

LOUT2

HPOUTR /

ROUT2

WM9712L

100 Ohm

LINE-OUT

SOCKET

(RIGHT)

1uF

Figure 24 Recommended Circuit for Line Output

The DC blocking capacitors and the load resistance together determine the lower cut-off frequency,

fc. Assuming a 10 k

load and C1, C2 = 10

fc = 1 / 2

) C

= 1 / (2

x 10.1k

x 1

F) = 16 Hz

Increasing the capacitance lowers fc, improving the bass response. Smaller values of C1 and C2 will

diminish the bass response. The function of R1 and R2 is to protect the line outputs from damage

when used improperly.

Production Data

WM9712L

PD Rev 4.0 December 2003

AC-COUPLED HEADPHONE OUTPUT

The circuit diagram below shows how to connect a stereo headphone to the WM9712L.

C2 220uF

HPOUTL

HPOUTR

HPGND = 0V

C1 220uF

WM9712L

Figure 25 Simple Headphone Output Circuit Diagram

The DC blocking capacitors C1 and C2 together with the load resistance determine the lower cut-off

frequency, fc. Increasing the capacitance lowers fc, improving the bass response. Smaller

capacitance values will diminish the bass response. For example, with a 16

load and C1 = 220

fc = 1 / 2

= 1 / (2

x 16

x 220

F) = 45 Hz

DC COUPLED (CAPLESS) HEADPHONE OUTPUT

In the interest of saving board space and cost, it may be desirable to eliminate the 220

F DC

blocking capacitors. This can be achieved by using OUT3 as a headphone pseudo-ground, as shown

below.

WM9712L

HPOUTL

HPOUTR

OUT3 = AVDD/2

Figure 26 Capless Headphone Output Circuit Diagram (OUT3SRC = 10)

As the OUT3 pin produces a DC voltage of AVDD/2, there is no DC offset between

HPOUTL/HPOUTR and OUT3, and therefore no DC blocking capacitors are required. However, this

configuration has some drawbacks:

The power consumption of the WM9712L is increased, due to the additional power
consumed in the OUT3 output buffer.

If the DC coupled output is connected to the line-in of a grounded piece of equipment,
then OUT3 becomes short-circuited. Although the built-in short circuit protection will
prevent any damage to the WM9712L, the audio signal will not be transmitted properly.

OUT3 cannot be used for another purpose

WM9712L

Production Data

PD Rev 4.0 December 2003

BTL LOUDSPEAKER OUTPUT

LOUT2 and ROUT2 can differentially drive a mono 8

loudspeaker as shown below.

LOUT2

ROUT2

WM9712L

INV = 1

Stereo: V

SPKR

= R-(-L) = L+R

Mono: V

SPKR

= M-(-M) = 2M

ROUT2VOL

LOUT2VOL

-1

Figure 27 Speaker Output Connection (INV = 1)

The right channel is inverted by setting the INV bit, so that the signal across the loudspeaker is the

sum of left and right channels.

COMBINED HEADSET / BTL EAR SPEAKER

In smartphone applications with a loudspeaker and separate ear speaker (receiver), a BTL ear

speaker can be connected at the OUT3 pin, as shown below.

HPOUTL

HPOUTR

HPGND = 0V

WM9712L

OUT3

BTL ear
speaker

Figure 28 Combined Headset / BTL Ear Speaker (OUT3SRC = 00)

The ear speaker and the headset play the same signal. Whenever the headset is plugged in, the

headphone outputs are enabled and OUT3 disabled. When the headset is not plugged in, OUT3 is

enabled (see "Jack Insertion and Auto-Switching")

COMBINED HEADSET / SINGLE-ENDED EAR SPEAKER

Instead of a BTL ear speaker, a single-ended ear speaker can also be used, as shown below.

HPOUTL

HPOUTR

HPGND = 0V

WM9712L

OUT3

ear speaker
(single-ended)

Figure 29 Combined Headset / Single-ended Ear Speaker (OUT3SRC = 01)

Production Data

WM9712L

PD Rev 4.0 December 2003

JACK INSERT DETECTION

The circuit diagram below shows how to detect when a headphone or headset has been plugged into

the headphone socket. It generates an interrupt, instructing the controller to enable HPOUTL and

HPOUTR and disable OUT3.

switch closes

on insertion

HPOUTL

HPOUTR

GPIO

interrupt

logic

100k

DBVDD

Figure 30 Jack Insert Detection Circuit

The circuit requires a headphone socket with a switch that closes on insertion. It detects both

headphones and phone headsets. Any GPIO pin can be used, provided that it is configured as an

input.

HOOKSWITCH DETECTION

The circuit diagram below shows how to detect when the "hookswitch" of a phone headset is pressed

(pressing the hookswitch is equivalent to lifting the receiver in a stationary telephone).

GPIO

interrupt

logic

MIC

HOOK
SWITCH

HPOUTL

HPOUTR

MICL/MICR

AGND

680

2.2k

MICBIAS

PHONE HEADSET

WM9712L

Figure 31 Hookswitch Detection Circuit

The circuit uses a GPIO pin as a sense input. The impedance of the microphone and the resistor in

the MICBIAS path must be such that the potential at the GPIO pin is above 0.7

DBVDD when the

hookswitch is open, and below 0.3

DBVDD when it is closed.

WM9712L

Production Data

PD Rev 4.0 December 2003

PACKAGE DRAWING - QFN

DM029.C

FL: 48 PIN QFN PLASTIC PACKAGE 7

0.9 mm BODY, 0.50 mm LEAD PITCH

INDEX AREA
(D/2 X E/2)

TOP VIEW

aaa

2 X

SEE DETAIL 2

E2/2

D2/2

aaa

2 X

Datum

SEE DETAIL 1

0.08

ccc

(A3)

SEATING PLANE

DETAIL 3

DETAIL 2

Terminal
tip

e/2

DETAIL 1

0.35mm

degrees

(A3)

Exposed lead

Half etch tie bar

Symbols

Dimensions (mm)

MIN

NOM

MAX

NOTE

0.80

0.90

1.00

0.30

0.25

0.18

7.00 BSC

5.25

5.15

5.00

7.00 BSC

0.5 BSC

5.15

5.25

5.00

0.30

0.4

0.50

0.02

0.05

0.20 REF

0.213

0.1

NOTES:
1. DIMENSION b APPLIED TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.15 mm AND 0.30 mm FROM TERMINAL TIP.
2. ALL DIMENSIONS ARE IN MILLIMETRES
3. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-002.
4. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
5. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE.

JEDEC, MO-220, VARIATION VKKD-2

Tolerances of Form and Position

aaa

bbb

ccc

0.1
0.2

0.15
0.10
0.10

REF

WM9712L

Production Data

PD Rev 4.0 December 2003

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Document Outline

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Document Outline

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: WM9712LSEFT