¡ Semiconductor

MSM7603/7603B

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¡ Semiconductor

MSM7603/7603B

Echo Canceler

GENERAL DESCRIPTION

The MSM7603/7603B is an improved version of the MSM7602 with basically the same
configuration, and offers twice the cancelable echo delay time of the MSM7602.
The MSM7603B I/O interface allows switching between m-law PCM and A-law PCM.
The MSM7603/7603B is a low-power CMOS IC device for canceling echo (in an acoustic system
or telephone line) generated in a speech path.
Echo is canceled, in digital signal processing, by estimating the echo path and generating a
pseudo echo signal.
When used as an acoustic echo canceler, the device can cancel the acoustic echo, between the loud
speaker and the microphone, which occur during hands free communication such as on a cellular
phone or a conference system phone.
When used as a line echo canceler, the device can cancel the line echo which returns due to
impedance mismatching in a hybrid.
In addition, a quality conversation is made possible by controlling the level and by preventing
howling through a howling detector, double talk detector, attenuation function and a gain
control function, and by controlling the low level noise by means of a center clipping function.
The use of a single chip codec, such as the MSM7704 (3 V) and MSM7533 (5 V), allows an economic
and efficient echo canceler to be configured.

FEATURES

· Can handle both acoustic and telephone line echoes.
· Switchable between m-law PCM and A-law PCM interfaces. (MSM7603B)
· Cancelable echo delay time:

MSM7603B-003 .............. 55 ms (max.)

· Echo attenuation

: 30 dB (typ.)

· Clock frequency

: 19.2 MHz

17.5 MHz to 20 MHz (when internal sync signal not used)

· Power supply voltage : 2.7 V to 5.5 V
· Package:

28-pin plastic SSOP (SSOP28-P-485-0.65-K) (Product name : MSM7603-003GS-K)

(Product name : MSM7603B-003GS-K)

E2U0064-18-82

This version: Aug. 1998

¡ Semiconductor

MSM7603/7603B

4/20

PIN DESCRIPTIONS

Pin

Symbol

Type

Description

NLP

HCL

ADP

SYNC

SCK

This is the control pin for the center clipping function to force

the SOUT output to a minimum value when the SOUT signal is

below 57 dBm0. Effective for reducing low-level noise.

"H": Center clip ON

"L": Center clip OFF

This is the through mode control pin.

When this pin is in the through mode the RIN and SIN data are

output to ROUT and SOUT. At the same time, the coefficient of

the adaptive FIR filter is cleared.

"H": Through mode

"L": Normal mode (echo canceler operates)

This is the AFF coefficient control pin which stops updating the

adaptive FIR filter (AFF) coefficient and sets it to a fixed value,

when the pin is configured to be the coefficient fix mode.

Used when holding the AFF coefficient which has been once

converged.

"H": Coefficient fix mode

"L": Normal mode (coefficient update)

This is the input pin for the sync signal for transmit/receive

serial data. This pin uses the external SYNC or SYNCO.

Inputs the PCM codec transmit/receive sync signal (8 kHz).

This is the clock input pin for transmit/receive serial data. It

uses the external SCK or the SCKO.

Input the PCM codec transmit/receive clock (64 to 2048 kHz).

¡ Semiconductor

MSM7603/7603B

5/20

PIN DESCRIPTIONS (Continued)

Pin

Symbol

Type

Description

RST

PWDWN

CLKIN

SYNCO

This is the input pin for the reset signal.

"L": Reset mode

"H": Normal operation mode

Due to initialization, input signals are disabled for 100 ms after reset

(after RST is returned from "L" to "H").

Input the basic clock during the reset.

Output pins during the reset are in the following sates :

High impedance: SOUT, ROUT

Not affected: SYNCO, SCKO

This is the power-down mode control pin for power down operation

"L": Power-down mode

"H": Normal operation mode

During power-down mode, all input pins are disabled and output

pins are in the following states :

High impedance : SOUT, ROUT

"L": SYNCO, SCKO

Reset after the power-down mode is released.

This pin controls the howling detect function that detects and

cancels a howling generated during hands-free talking for

acoustic system.

This function is used to cancel acoustic echoes.

"L": Howling detector ON

"H": Howling detector OFF

This is the input pin for external input for the basic clock.

Input the basic clock (17.5 to 20 MHz).

When the internal sync signal (SYNCO, SCKO) is used, input the

basic clock of 19.2 MHz.

This is the output pin for the 8 kHz sync signal for the PCM codec.

Connect to the SYNC pin and the PCM codec transmit/receive sync

pin.

Leave open if using an external SYNC.

(m/A)

Used for MSM7603B only.

This is the input pin for m-law PCM/A-law PCM interface select

signal.

"L": A-law PCM interface

"H": m-law PCM interface

For MSM7603, apply V

(PLL)

This is the power supply pin for the PLL circuit used for the basic

clock.

Insert a 0.1 mF capacitor with excellent high frequency

characteristics between V

(PLL) and V

(PLL).

(PLL)

This is the ground pin for the PLL circuit used for the basic clock.

¡ Semiconductor

MSM7603/7603B

6/20

PIN DESCRIPTIONS (Continued)

Pin

Symbol

Type

Description

ROUT

SOUT

SIN

RIN

SCKO

ATT

This is the pin for the input signal by which the gain controller

for the RIN input is controlled. The pin also controls RIN input

level and prevents howling.

The gain controller adjusts the RIN input level when it is 20

dBm0 or above. RIN input levels from 20 to 11.5 dBm0 will be

suppressed to 20 dBm0 in the attenuation range from 0 to 8.5 dB.

RIN input levels above 11.5 dBm0 will always be attenuated by

8.5 dB.

"H": Gain control ON

"L": Gain control OFF

"H" is recommended for performing echo cancellation.

This is the output pin for the transmit clock signal (256 kHz) for

the PCM codec.

Connect to the SCK pin and the PCM codec transmit/receive clock

pin.

Leave open when using an external SCK.

This is the control pin for the ATT function which prevents howling

by attenuators (ATT) for the RIN input and SOUT output.

If there is input only to RIN, then the ATT for the SOUT output is

activated.

If there is no input to SIN or there is input to both SIN and RIN,

then the ATT for the RIN input is activated.

Either the ATT for the RIN output or the ATT for the SOUT is

always activated in all cases, and the attenuation of ATT is 6 dB.

"H": ATT OFF

"L": ATT ON

"L" is recommended for performing echo cancellation.

This is the receive serial data input pin.

Input the PCM signal synchronized to SYNC and SCK.

Data is read at the falling edge of SCK.

This is the transmit serial data input pin.

Input the PCM signal synchronized to SYNC and SCK.

Data is read at the falling edge of SCK.

This is the output pin for receive serial data.

Outputs the PCM signal synchronized to SYNC and SCK.

This pin is in high impedance state during the absence of data output.

This is the output pin for transmit serial data.

Outputs the PCM signal synchronized to SYNC and SCK.

This pin is in high impedance state during the absence of data output.

(TEST)

This pin is for MSM7603B only and not used. Should be left open.

In MSM7603 it is an NC pin.

¡ Semiconductor

MSM7603/7603B

7/20

ABSOLUTE MAXIMUM RATINGS

Parameter

Power Supply Voltage

Input Voltage

Power Dissipation

Storage Temperature

Symbol

STG

Condition

Ta = 25°C

Rating

0.3 to

+ 7

0.3 to V

+ 0.3

55 to

+150

Unit

°C

RECOMMENDED OPERATING CONDITIONS

Parameter

Power Supply Voltage

High Level Input Voltage

Low Level Input Voltage

Operating Temperature

Symbol

Condition

Min.

2.7

2.0

Unit

°C

Typ.

3.3

+25

Max.

3.6

0.5

+85

= 2.7 V to 3.6 V)

Parameter

Power Supply Voltage

High Level Input Voltage

Low Level Input Voltage

Operating Temperature

Symbol

Condition

Min.

4.5

2.4

Unit

°C

Typ.

+25

Max.

5.5

0.8

+85

= 4.5 V to 5.5 V)

¡ Semiconductor

MSM7603/7603B

8/20

ELECTRICAL CHARACTERISTICS

DC Characteristics

= 2.7 V to 3.6 V, Ta = 40°C to +85°C)

Parameter

High Level Output Voltage

Low Level Output Voltage

High Level Input Current

Low Level Input Current

High Level Output Leakage Current

Low Level Output Leakage Current

Power Supply Current

(Operating)

Power Supply Current

(Standby)

Input Capacitance

Output Load Capacitance

Symbol

OZH

OZL

DDO

DDS

LOAD

Condition

= 40 mA

= 1.6 mA

= V

PWDWN = "L"

Min.

2.2

Typ.

0.1

0.5

Max.

0.4

Unit

= 4.5 V to 5.5 V, Ta = 40°C to +85°C)

Parameter

High Level Output Voltage

Low Level Output Voltage

High Level Input Current

Low Level Input Current

High Level Output Leakage Current

Low Level Output Leakage Current

Power Supply Current

(Operating)

Input Capacitance

Output Load Capacitance

Power Supply Current

(Standby)

Symbol

OZH

OZL

DDO

DDS

LOAD

Condition

= 40 mA

= 1.6 mA

= V

PWDWN = "L"

Min.

Typ.

4.2

0.1

0.5

Max.

0.4

Unit

¡ Semiconductor

MSM7603/7603B

10/20

AC Characteristics

Parameter

Clock Frequency

When Internal Sync Signal is not used

Clock Cycle Time

When Internal Sync Signal is not used

Clock Duty Ratio

Clock "H" Level Pulse Width

fc = 19.2 MHz
Clock "L" Level Pulse Width

fc = 19.2 MHz
Clock Rise Time

Clock Fall Time

Sync Clock Output Time

Internal Sync Clock Frequency

Internal Sync Clock Output Cycle Time

Internal Sync Clock Duty Ratio

Internal Sync Signal Output Delay Time

Internal Sync Signal Period

Internal Sync Signal Output Width

Transmit/Receive Sync Clock Frequency

Transmit/Receive Sync Clock Cycle Time

Transmit/Receive Sync Clock Duty Ratio

Transmit/Receive Sync Signal Period

Sync Timing

Sync Signal Width

Receive Signal Setup Time

Receive Data Input Time

Serial Output Delay Time

Symbol

MCK

DMC

MCH

MCL

DCM

DCO

DCC

CYO

WSO

SCK

DSC

CYC

WSY

Min.

17.5

50.0

20.8

0.488

123

SCK

Typ.

19.2

52.08

256

3.9

125

SCK

Max.

20.0

57.14

31.3

2048

15.6

CYC

-t

SCK

Min.

17.5

50.0

20.8

0.488

123

SCK

Typ.

19.2

52.08

256

3.9

125

SCK

Max.

20.0

57.14

31.3

2048

15.6

CYC

-t

SCK

Unit

MHz

kHz

= 2.7 V to 3.6 V

= 4.5 V to 5.5 V

(Ta = 40°C to +85°C)

Reset Start Time

DRS

Reset End Time

DRE

Processing Operation Start Time

DIT

100

Reset Signal Input Width

Power Down Start Time

Power Down End Time

DPS

111

DPE

Control Pin Hold Time (RST)

DHR

Control Pin Setup Time (RST)

DSR

111

Control Pin Setup Time

DTS

Control Pin Hold Time

DTH

160

Reset Pulse Width Immediately after Power Down t

WPR

Receive Signal Hold Time

¡ Semiconductor

MSM7603/7603B

12/20

Serial Output Timing

Operation Timing After Reset

Power Down Timing

DPS

DPE

Internal Operation

Processing Start

Power Down

PWDWN

WPR

Invalid

RST

SCK

SYNC

SOUT

ROUT

MSB

CYC

SCK

, t

SCK

WSY

LSB

MSB

DSC

High-Z

DRS

RST

DRE

Internal operaion

Processing Start

DIT

Reset

Initialization

*Reset timing can be asynchronous.

* INT is invalid during the shaded interval.

¡ Semiconductor

MSM7603/7603B

14/20

HOW TO USE THE MSM7603/7603B

The MSM7603/7603B cancels, based on the RIN signal, the echo which returns to SIN.
Connect the base signal to the R side and the echo-generated signal to the S side.

Connection Methods According to Echoes

Example 1:

Canceling acoustic echo (to handle acoustic echo from line input)

AFF

ROUT

SIN

RIN

SOUT

MSM7603

MSM7603B

CODEC

Line input

Acoustic echo

Example 2:

Canceling line echo (to handle line echo from microphone input)

AFF

RIN

SOUT

ROUT

SIN

MSM7603

MSM7603B

CODEC

Lin echo

Microphone input

Example 3: Canceling of both acoustic and line echo

(to handle both acoustic echo from line input and line echo from microphone input)

SIN

ROUT

CODEC

Line input

Acoustic echo

AFF

ROUT

SIN

MSM7603

MSM7603B

AFF

SOUT

RIN

MSM7603

MSM7603B

RIN

SOUT

Microphone input

For acoustic echo

Line echo

CODEC

For line echo

¡ Semiconductor

MSM7603/7603B

15/20

ECHO CANCELER CHARACTERISTICS DIAGRAM
(for

m-law and A-law, and for reference only)

E. R. L. vs. echo attenuation

Echo attenuation [dB]

E. R. L. [dB]

Measurement Conditions :
RIN input = 10 dBm0 5 kHz band white noise
Echo delay time T

= 50 ms

ATT, GC, NLP = OFF
Power supply voltage 5 V

50 40 30 20 10

RIN input level vs. echo attenuation

Echo attenuation [dB]

RIN input level [dBm0]

Measurement Conditions :
RIN input: 5 kHz band white noise
Echo delay time T

= 50 ms

E.R.L. = 6 dB
ATT, GC, NLP = OFF
Power supply voltage 5 V

Echo delay time vs. echo attenuation

Echo attenuation [dB]

Echo delay time [ms]

Measurement Conditions :
RIN input = 10 dBm
5 kHz band white noise

E.R.L. = 6 dB
ATT, GC, NLP = OFF
Power supply voltage 5 V

Note:

Above characteristics are for the MSM7533 (V

5 V, m-law CODEC interface). For the

MSM7704 (V

3 V, m-law interface) the characteristics are basically the same except

for input and output levels. Refer to the PCM CODEC data sheet.

MSM7533

(for both transmit and receive)

0 dBm0 = 0.85 Vrms = 0.8 dBm (600 W)

MSM7704

(for transmit side)

0 dBm0 = 0.35 Vrms = 6.9 dBm (600 W)

(for receive side)

0 dBm0 = 0.5 Vrms = 3.8 dBm (600 W)

¡ Semiconductor

MSM7603/7603B

17/20

APPLICATION CIRCUIT

Bidirectional Connection Example

Microphone input

Speaker output

21
22

13
12
14
10
16
19

5
6

AIN1
GSX1
AOUT1

DOUT1
DIN1
XSYNC
RSYNC
BCLK
A / m
PDN
CHP

AIN2

GSX2

AOUT2

DOUT2

DIN2

SGC

24
23
2

14
11

8
1

C10 C11

Line input

Line output

(AG)

MSM7603/7603B

For cancelation of

acoustic echo

MSM7603/7603B

For cancelation of line echo

25
26

16
18

20
28

PWDWN

RST

CLK

27
24

19
17

15
23

SIN
ROUT

SYNC
SCK

SYNCO
SCKO

RST

PWDWN

CLKIN

SOUT

RIN

NLP
HCL

ATT

(P)

ADP

(m / A)

(P)

SOUT
RIN

NLP
HCL

ATT
GC

(m / A)

(P)

ADP

(P)

SIN

ROUT

SYNC

SCK

SYNCO

SCKO

RST

CLKIN

PWDWN

27
24

19
17

7
15
23

25
26

16
18

6
20
28

R1=20 kW
R2=20 kW
R3=2.2 kW
R4=10 kW
R9=10 kW

C1=1 mF
C2=10 mF
C3=0.1 mF
C4=0.1 mF

R5=20 kW
R6=20 kW
R7=2.2 kW
R8=10 kW
R10=10 kW

C5=1 mF
C6=10 mF
C7=0.1 mF
C8=0.1 mF
C9=0.1 mF
C10=10 mF
C11=0.1 mF

Use the MSM7704-01GS-VK as a PCM CODEC when V

3 V is used.

The MSM7533 is pin compatible with the MSM7704.

2ch CODEC

MSM7533VGS-K

R10

(TEST)

¡ Semiconductor

MSM7603/7603B

18/20

NOTES ON USE

1. Set echo return loss (ERL) to be attenuated. If the echo return loss is set to be

amplified, the echo cannot be eliminated.
Refer to the characteristics diagram for E. R. L. vs. echo attenuation quantity.

2. Set the level of the analog input so that the PCM codec does not overflow.

3. The recommended input level is 10 to 20 dBm0. Refer to the characteristics

diagram for the RIN input level vs. echo attenuation quantity.

4. Applying the tone signal to this echo canceler for long duration may decrease echo

attenuation.
When used with the HD pin "L" (howling detector ON), this echo canceler may
operate faultily if, while a signal is input to the RIN pin, a tone signal with a higher
level than the signal being input to RIN is input to the SIN pin.
A signal should therefore be input either to the RIN pin or to the SIN pin. If,
however, the tone signal is input to the SIN pin while a signal is input to the RIN pin,
the ADP, HD, or HCL pin must be set to "H".

5. For changes in the echo path (retransmit, circuit switching during transmission,

and so on), convergence may be difficult.
Perform a reset to make it converge.
If the state of the echo path changes after a reset, convergence may again be difficult.
In cases such as a change in the echo path, perform a reset each time.

6. When turning the power ON, set the PWDWN pin to "1" and input the basic clock

simultaneously with power ON.
If the device is put into power down mode immediately after power ON, be sure
to input 10 or more clocks of the basic clock before setting to the power down mode.

7. After power ON, be sure to reset the device.

8. After the power down mode is released (when PWDWN pin is changed to a "1" from

a "0"), be sure to reset the device.

9. If this canceler is used to cancel acoustic echoes, an echo attenuation may be less

than 30 dB.

¡ Semiconductor

MSM7603/7603B

19/20

EXPLANATION OF TERMS

Attenuating Function :

This function prevents howling and controls the noise level with
the attenuator for the RIN input and SOUT output. Refer to the
explanation of pins (ATT pin).

Echo Attenuation :

If there is talking (input only to RIN) in the path of a rising echo
arises, the echo attenuation refers to the difference in the echo
return loss (canceled amount) when the echo canceler is not used
and when it is used.
Echo attenuation = (SOUT level during through mode operation)
(SOUT level during echo canceler operation) [dB]

Echo Delay Time :

This is the time from when the signal is output from ROUT until it
returns to SIN as an echo.

Acoustic Echo :

When using a hands-free phone, for example, the signal output
from the speaker echoes and is input again to the microphone. The
return signal is referred to as acoustic echo.

Telephone Line Echo :

This is a signal which is delayed midway in a telephone line and
returns as an echo, due to reasons such as a hybrid impedance
mismatch.

Gain Control Function :

This function prevents howling and controls the sound level by
with a gain controller for the RIN input. Refer to the explanation
of pins (GC pin).

Center Clipping Function : This function forces the SOUT output to a minimum value when

the signal is below 57 dBm0. Refer to the explanation of pins (NLP
pin).

Double Talk Detection :

Double talk refers to a state in which the SIN and RIN signals are
input simultaneously. In a double talk state, a signal other than the
echo signal which is to be canceled can be input to the SIN input,
resulting in malfunction.
The double talk detector prevents such malfunction of the canceler.

Howling Detection :

This is the oscillating state caused by the acoustic coupling between
the loud speaker and the microphone during hands-free talking.
Howling not only interferes with talking, but can also cause
malfunction of the echo canceler.
The howling detector prevents such malfunction and howling.

Echo Return Loss (ERL) :

When the signal output from ROUT returns to SIN as an echo, ERL
refers to how much loss there is in the signal level during ROUT.
ERL = (ROUT level) (SIN level of the ROUT signal which returns
as an echo) [dB]
If ERL is positive (ROUT > SIN), acts as an attenuator.
If ERL is negative (ROUT < SIN), acts as an amplifier.

PHS :

Personal Handyphone System

¡ Semiconductor

MSM7603/7603B

20/20

(Unit : mm)

PACKAGE DIMENSIONS

Notes for Mounting the Surface Mount Type Package

The SOP, QFP, TSOP, SOJ, QFJ (PLCC), SHP and BGA are surface mount type packages, which
are very susceptible to heat in reflow mounting and humidity absorbed in storage.
Therefore, before you perform reflow mounting, contact Oki's responsible sales person for the
product name, package name, pin number, package code and desired mounting conditions
(reflow method, temperature and times).

SSOP28-P-485-0.65-K

Package material
Lead frame material
Pin treatment
Solder plate thickness
Package weight (g)

Epoxy resin
42 alloy
Solder plating
5 mm or more
0.39 TYP.

Mirror finish

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