129 Morgan Drive, Norwood MA 02062 1

voice: (781) 551-9450 fax: (781) 440-9528 email: sales@apogeeddx.com

DDX All-Digital, High Efficiency

Evaluation Amplifier

GENERAL DESCRIPTION

The EB-2100x is an evaluation amplifier that
showcases Apogee's all-digital, high efficiency Direct
Digital Amplification (DDX

) technology. The board

features a DDX-2000 Controller and DDX-2100
Power Device which provide full digital audio
preamplifier functions and power amplification. The
board includes both coaxial and optical S/PDIF
interfaces, digital volume and balance controls and
local power regulation to operate from a single supply
voltage.

The EB-2100x is available in both a stereo 50W (EB-
2100S) and a mono 100W version (EB-2100M).

ORDERING INFO

EB-2100S DDX stereo amplifier board
EB-2100M DDX mono amplifier board

FEATURES

DDX-2000/2100 CHIP SET

OPERATION 9 to 36 VDC

2x50W into 8

@ 1% THD

1x100W into 4

@ 1% THD

TYPICAL PERFORMANCE

0.07% THD+N (1W, 1kHz)

90 dB SNR (50Wrms, A-weighted)

88% EFFICIENCY

DIGITAL INPUT

S/PDIF COAX/OPTICAL

S LOOP THROUGH

DIGITAL PREAMP FEATURES

VOLUME

BALANCE

ANTICLIPPING

AUTOMATIC MUTE

EB-2100x BLOCK DIAGRAM

EB-2100x

DDX-2000

Controller

DDX-2100

Power Device

Filter

S Serial
PCM

Left

Right

PWM1

V+

PWM2

Volume

Mute

Reset

Clock

Power Down

+VL

S/PDIF
Receiver

Coax or
Optical
Digital Audio

_______________ __ EB-2100x

Details are subject to change without notice.

DESIGN OVERVIEW

The EB-2100x is an all-digital amplifier
evaluation board that demonstrates Apogee's
DDX-2000/2100 chip set solution. The board
features coaxial and optical S/PDIF digital
interfaces, volume and balance controls,
expansion headers for off-board processing, and
local power regulation enabling single supply
operation from 10 to 36VDC. The all-digital
amplifier board may be configured as either 2 x
50W into 8

or 1 x 100W into 4

DDX-2000/2100 OVERVIEW

The DDX-2000 Controller is a 3.3V digital
integrated circuit that converts serial PCM digital
audio signals into Apogee's patented damped
ternary outputs. The device supports two
modes of digital volume control, muting and anti-
clipping functions. A block diagram of the
device is shown in Figure 1.

Figure 1 - DDX-2000 Functional Diagram

The DDX-2100 Power Device is a dual channel
H-Bridge that can deliver over 50 watts per
channel of audio output power. The DDX-2100
includes; a logic interface, integrated bridge
drivers, high efficiency MOSFET outputs and
protection circuitry. Two logic level signals per
channel are used to control high-speed
MOSFET switches to connect the speaker load
to the input supply or to ground in a bridge
configuration, according to Apogee's patented
damped ternary PWM. The DDX-2100 includes
over-current and thermal protection, and under-
voltage lockout with automatic recovery. A
thermal warning status is also provided.

Figure 2 - DDX-2100 Block Diagram

SCHEMATIC DESCRIPTION

S/PDIF INPUT INTERFACE (FIG. 3A)

The EB-2100x accommodates either a coaxial
or an optical S/PDIF digital audio interface.
Either input may be selected by moving jumper
J2. Connect J2 pins 1-2 for coaxial or J2 pins 2-
3 for optical S/PDIF. A Crystal CS8415A digital
audio interface receiver is utilized to convert the
incoming S/PDIF signal to serial I

S used by the

DDX-2000. The receiver also recovers a 256*Fs
clock synchronized to the incoming signal which
is used as the master clock to the DDX-2000.
The design will support sample rates from below
32kHz to above 48kHz. The receiver PLL out-
of-lock signal is used to mute the amplifier's
output when a valid S/PDIF signal is not present.
Zero ohm jumpers R6,R9,R10,R11,R42 are
provided to disconnect the outputs of the S/PDIF
receiver from the inputs to the DDX-2000 so that
external signals may be applied via the
expansion header J7 (see Fig. 3D).

DIGITAL SIGNAL PROCESSING (FIG. 3B)

The DDX-2000 converts serial I

S digital audio

signals into pulse-width-modulated digital
signals output at 8*Fs, according to Apogee's
patented damped ternary architecture. Signals
from the S/PDIF receiver are applied as inputs
to the DDX processor and signals from the DDX
processor are applied to the inputs of the DDX
power stage.

A low-cost microcontroller with an ADC is used
to implement the volume and balance controls.
The amplifier's volume and balance levels are

SERIAL

INTERFACE

VOLUME/

GAIN

PWM

GENERATION

ANTI-

CLIPPING

SYSTEM

CLOCKING

SCLK

SDATA

LRCLK

VMODE

VCLK/UP

VDATA/DN

ACE

OUTL[1:2]

OUTR[1:2]

XI XO LPIN LPOUT

MUTE

Logic I/F

and Decode

Left

H-Bridge

Protection

Circuitry

INL[1:2]

INR[1:2]

PWRDN

OUTPL

FAULT

TRI-STATE

OUTNL

OUTPR

OUTNR

TWARN

Regulators

Right

H-Bridge

_______________ __ EB-2100x

Details are subject to change without notice.

adjusted using two potentiometers. The DC
voltage set by the potentiometers is read by the
microcontroller that interfaces to the volume
serial port of the DDX-2000. The DDX-2000 has
independent volume control registers that have
an adjustment range from 82.5dB to +12.0dB in
0.75dB increments. A 0dB switch setting is
included to signal the microcontroller to set the
volume level for both channels to be unity gain.
This setting is particularly useful for audio
measurements.

The EB-2100x permits three separate methods
for clocking the DDX-2000. The default is via
the 256*Fs recovered clock output from the
S/PDIF receiver IC. The second is via the
expansion header J7 used to apply an external
clock source to synchronize, for example,
multiple DDX-2000 ICs to the same clock. Zero-
ohm jumper R35 is installed to pass either of
these clock sources to the DDX-2000 master
clock input. The last method is asynchronous
from an external crystal. The DDX-2000
contains a crystal oscillator which may be used
for single sample-rate applications. Oscillator
circuit Y1, C30, C37, R24, R26 may be
populated and jumper R35 removed for
applications where a 256*Fs clock source is not
convenient. The DDX-2000 tolerates a sample
rate mismatch of +/-0.2% about the crystal
frequency without performance degradation.
The crystal footprint is a surface mount Epson
MA-506.

There are additional provisions for
demonstrating DDX-2000 functionality. The
GCEN flag is used to disable the anticlipping
function and is controlled by DIP rocker switch
SW1. Jumper R29 is provided to change the
serial port mode on the DDX-2000 from I

S to

left-justified to accommodate an external set of
signals. Jumpers R13, R14, R30 are provided
for test modes and must not be changed. A
channel reverse flag is provided which inverts
LRCLK causing left channel data to be output on
the right channel and vice versa. This function
is intended to be used for multiple amplifiers
configured as mono when used in a
multichannel audio demonstration.

POWER OUTPUT (FIG. 3C)

The DDX-2100 provides power amplification by
translating logic level PWM signals into power
level signals. These power level signals are
applied to a passive two-pole lowpass filter to
reconstruct the audio signal providing power to

the load. The output filter functions to attenuate
unwanted high frequency signals from reaching
the load. A filter design for 8

loads is shown in

the Fig. 3C schematic for reference.

The DDX-2100 is designed for stereo operation
as either two independent full-bridges or for
mono operation as one full-bridge with twice the
current capability, enabling higher output power.
The EB-2100x is designed to demonstrate both
configurations via component substitutions. The
schematic notes in Fig. 3C detail component
changes to convert from stereo to mono
operation. Evaluation boards configured as
either stereo or mono may be ordered with the
appropriate part number designations. Jumpers
R19, R22, R25, R33 are used to configure PWM
inputs for stereo operation. Jumpers R17, R23,
R27, R36 are used to configure PWM inputs for
mono operation. Jumpers JP1 and JP3 parallel
the output bridges enabling higher output
current. Jumpers JP2 and JP4 parallel the
output filter sections to a 4

load. Capacitor

C29 is the differential capacitor required for the
4

filter only.

In applications where only mono 100W /
4

operation is desired, e.g. subwoofer, the

output filter may be simplified. Two filter
sections may be employed in lieu of sections in
parallel. Inductors may be ½ the value with
twice the current rating. Capacitors are double
the value and resistors are ½ the value at twice
the power rating.

Snubbers are employed to protect the output
MOSFETs from inductive transients. Peak
voltage on the DDX-2100 output and power pins
must not exceed 40V. Output snubbers for the
stereo implementation are R15,C23 and
R31,C40 and the snubber for the mono
implementation is R21,C32.

Input protection is provided for the amplifier by
diode D1. D1 will protect from overvoltage and
reverse power applications by shunting the
power supply.

A thermal warning indicator is activated by the
DDX-2100 when its junction temperature
exceeds +130

C. The thermal warning output is

used to force the power LED to change color
from green to red forecasting the potential of an
overtemperature shutdown.

_______________ __ EB-2100x

Details are subject to change without notice.

HEADERS / REGULATORS (FIG. 3D)

The EB-2100x features local power regulation to
facilitate operation from a unipolar +10 to +36
VDC supply. Alternatively, auxiliary power may
be applied at J8 (removing bead L7) separating
logic and output power supplies. Output from
the onboard +5V regulator is available on the J6
test header. Output from the onboard +3.3V
regulator is available on the J7 expansion
header. There is capability available to power
external circuits from either the +5V or the +3.3V
supplies or a combination not to exceed a total
current of 0.33A.

Expansion header J7 is provided to monitor or
apply input signals to the DDX-2000. Jumper
R42 may be removed to pass serial data
provided by an external processor. Test header
J6 is provided to monitor signals output from the
DDX-2000. Signals INLC, INLD, INRC, INRD
are driven low by the DDX-2000 and are used
for test purposes only. DIP switch SW1 is used
for control functions: POS1 reverses data
channels when open, normal when closed;
POS2 sets unity gain for test when closed,
normal when open; POS3 forces the DDX-2100
into low power mode when closed, normal when
open; POS4 disables the anticlipping function
when closed, normal when open.

Supervisor U8 is used for power-on-reset,
power-off sequencing, and as a convenient
means of commanded reset via pushbutton.

ADDITIONAL INFORMATION

Bill of Materials

A bill of materials for the evaluation board is
provided in Table 1 for reference. Note
equivalent components from alternate
manufacturers may be substituted. No warranty
of system performance is implied by Apogee
through use of the reference bill of materials.

Power Dissipation/Heat Sink Requirements

The DDX-2100 is a high efficiency dual channel
design intended for audio applications needs up
to 50 Watts RMS per channel. The power
dissipation of the device will depend primarily on
the supply voltage, load impedance, and output
modulation level. The thermal performance of
the evaluation board is consistent with a steady-

state duty rating of 50W RMS per channel with
both channels driven into 8

The DDX-2100 surface mount package includes
an exposed thermal pad on the top of the device
to provide a direct thermal path from the
integrated circuit to the heat sink. For continuous
duty rated applications, careful consideration
must be made to the overall thermal design.

Performance Measurements

Typical performance measurements for the
evaluation board are shown in Figs 4 through
11.

Class D amplifiers produce measurable
switching distortion outside the audio bandwidth.
Apogee's DDX amplifier uses a patented PWM
modulation scheme that significantly reduces the
size of these products compared to typical Class
D designs. However, in order to obtain accurate
performance measurements in the audio
bandwidth (i.e., 20Hz to 20kHz) additional
filtering is required.

The Typical Performance data in was taken
using a brick wall filter with a break frequency of
22kHz. This type of filter is often provided as
part of audio measurement systems.

OPERATING INSTRUCTIONS

Refer to Fig. 12 evaluation amplifier assembly
drawing. Attach a regulated power supply at J3
set between +10V and +36VDC. At +36V, the
power supply must be capable of delivering 4A
minimum for two channels. Attach a digital
audio input source at either the coaxial or optical
S/PDIF connectors. Select the digital input
source via J2. Connect 8 Ohm speakers to J4
(left speaker) and J5 (right speaker). Configure
SW1 as POS1 closed, POS2,3,4 open. Note,
the speaker outputs are bridged. Do not ground
any speaker connections, e.g. through an
oscilloscope. Apply power, digital source
material and enjoy!

________________ __ EB-2100x

Details are subject to change without notice.

FIG. 3C - DDX EVAL AMPLIFIER SCHEMATIC: POWER OUTPUT

C19
470nF
FILM

R17
0

C52
100nF

R15
20
1/4W

LSPKR+

JP1
OJMP

22uH

C31

100nF

C28
100nF

R37
6.2
1/4W

RSPKR+

C53

1uF

50V

R25

JP4
OJMP

J3
PWR

C54

1uF

50V

+36V

C41
100nF

36V

1.5kW

DDX2100

GNDS

OUTNR

VCC2N

PGND2N

PGND2P

VCC2P

OUTPR

OUTNL

VCC1N

PGND1N

PGND1P

VCC1P

OUTPL

GNDREF

GNDR1

VREG1

CONFIG

PWRDN

TRI-STATE

FAULT

TWARN

INLA

INLB

INRA

INRB

VREG2

VSIG

R23

IN1B

C29

1uF

C17
100nF

C33
100nF
FILM

C26

100nF

C35

100nF

Note: For Mono:

Install C32, R21, R23, R27, R36, R17, JP1,2,3,4.

Remove R19,R25, R33, R22.

IN1B

IN2B

LEFT

1
2

JP2
OJMP

C25
100nF

C36
100nF

C32

680pF

nPWRDN

C34

100nF

R19

C20

100nF

C22

100nF

C18
100nF

THWARN

IN1A

22uH

C15
100nF
FILM

C23
330pF

+3.3V

R20

10k

R33

R31
20
1/4W

C16

2200uF

50V

C40
330pF

R32
6.2
1/4W

22uH

R18
6.2
1/4W

JP3
OJMP

R27

RSPKR-

R16
6.2
1/4W

+36V

RIGHT

1
2

R22
0

IN2A

IN1B

C27
100nF
FILM

LSPKR-

R21

10
1/4W

IN1A

22uH

C43
100nF
FILM

CONFG

R36

C38
470nF
FILM

FIG. 3D - DDX EVAL AMPLIFIER SCHEMATIC: HEADERS / REGULATORS

+36V

MUTE

MCLK

R40
18k

IN2C

TSW-106-07-S-D-LL

1
3
5
7
9
11

2
4
6
8

10
12

SW1

SW DIP-4

1
2
3
4

8
7
6
5

nRESET

IN1B

R42

2N3904

+3.3V

IN1C

SWAP

IN1A

nPWRDN

R44

18K

LM2594M-5.0

FBK

OUT

GND

VIN

nON/OFF

220uH

Logic Pwr

1
2

VDATA

GCEN

IN2A

C44
100uF

16V

IN2B

C47

10nF

SDOUT

C46
100nF

R38
300

+3r3V

+5V

Q2
2N3904

D2
GRN/RED

VCLK

C51
100nF

IN2D

VMODE

SW2

RESET

R41

2.2k

+3r3V

LRCLK

U7
LM2937IMP-3.3

OUT

GND

TAB

THWARN

R39
300

0dB

DS1233A-10

Vcc

GND

nRESET

C45
100nF

SCLK

C50
100nF

SDATA

IN1D

TSW-105-07-S-D-LL

1
3
5
7
9

2
4
6
8

C49
100uF
16V

R43

300

nRESET

C48
100uF
50V

D3
B140
1A
40V

Ferrite 600
@100MHz

________________ __ EB-2100x

Details are subject to change without notice.

TABLE 1 - DDX EVALUATION AMPLIFIER BOM

Item

Quantity

Reference

Description

Mfr. Part No.

Mfr.

C1,C2,C6,C7,C9,C18,C20,

Capacitor, Ceramic, Y5V, 100nF, 25V, +80/ -20%

ECJ-2VF1E104Z

Panasonic

C28,C35,C39,C45,C46,C51

C26,C31,C50

Capacitor, Ceramic, Y5V, 100nF, 50V, +80/ -20%

ECJ-2VF1H104Z

Panasonic

C53,C54

Capacitor, Tantalum, 1uF, 35V, 20%

ECS-TIVX105R

Panasonic

C22,C34

Capacitor, Ceramic, X7R, 100nF, 50V,
10%

C17,C25,C36,C41,C52
C34

Capacitor, Ceramic, X7R, 100nF, 50V, 10%

ECJ-3VB1H104K

Panasonic

C15,C27,C33,C43

Capacitor, Polyester Film, 100nF, 100V, 5%

ECJ-2VF1H103Z

Centralab

C3,C4,C5,C11,C12,C14,C21,C24,C47

Capacitor, Ceramic, Y5V, 10nF, 50V, +80/ -20%

ECJ-2VF1H103Z

Panasonic

C42

Capacitor, Ceramic, X7R, 10nF, 50V, 10%

ECU-V1H103KBG

Panasonic

Capacitor, Ceramic, X7R, 82nF, 25V, 10%

ECJ-2VB1E823K

Panasonic

C10

Capacitor, Ceramic, X7R, 2.2nF, 50V, 10%

ECU-V1H222KBN

Panasonic

C19,C38

Capacitor, Polyester Film, 470nF, 63V, 5%

2222 370 12474

Centralab

C16

Capacitor, Aluminum Electrolytic, M-Series, 2200uF, 50V, 20%

ECA-1HM222

Panasonic

C23,C40

Capacitor, Ceramic, X7R, 330pF, 50V, 10%

ECJ-2VC1H331J

Panasonic

C32

Capacitor, Ceramic, X7R, 680pF, 50V, 10%

ECJ-2VC1H681J

Panasonic

C29

Capacitor, Polyester Film, 1uF, 63V, 5%

2222 370 12105

Centralab

C30,C37

Capacitor, Ceramic, NPO, 10pF, 50V, 10%

ECU-V1H100DCN

Panasonic

C48

Capacitor, Aluminum Electrolytic, HFS-Series, 100uF, 50V, 20%

ECE-A1HFS101

Panasonic

C13,C44,C49

Capacitor, Aluminum Electrolytic, HFS-Series, 100uF, 10V, 20%

ECE-A1AFS101

Panasonic

Diode, TVS, 1.5KW, Uni-Directional, 30V Standoff, 35.8VBR, 7%, SMCJ

SMCJ30A

Diodes Inc.

LED, T1 3/4, Green/Red, White Diffused

LN11WP23

Panasonic

Diode, Schottkey Barrier, SMD, 1A, 40V

B140

Diodes Inc.

JP1,JP2,JP3,JP4

Buss Wire Jumper, 22 AWG, 0.1"

RCA Phono connector, Right Angle PCB, Tin Plate

901

Keystone

Header, 3-pin, 1X3, 0.10 spacing.

TSW-103-07-S-S-LL

Samtec

J3,J4,J5

Connector, Terminal Block Plug, 5.08mm, 12-30 AWG, Two-position

EMKDS 2.5/2-5.08

Phoenix Contact

Header, 10-pin, 2X10, 0.10 spacing.

TSW-105-07-S-D-LL

Samtec

Header, 12-pin, 2X10, 0.10 spacing.

TSW-106-07-S-D-LL

Samtec

L1,L2,L7

Ferrite Chip, EMI Supression, SMD, 600 Ohm @100MHz, 0.5A

HZ0805E601R-00

Steward

L3,L4,L5,L6

Inductor, 22uH, 2.6A, .046 DCR

RL-5480-4-22

Renco

ALTERNATE

Inductor, 22uH, 3.5A, .047 DCR

CTDO5022P-223

Central Technologies

Inductor, 220uH, 10%, .64A, .68DCR

CT622LY-221K

Central Technologies

Q1, Q2

Transistor, NPN, 330mW, 40V CEO

FMMT3904

Zetex

Resistor, Chip, Thk Film, 75, 5%, 1/10W, 200ppm

ERJ-6GEYJ750V

Panasonic

Potentiometer, 10k, 9mm Audio, Linear taper, Right angle

EVU-E2AF25B14

Panasonic

Potentiometer, 10k, 9mm Audio, Linear taper, Right angle, Center Detent

EVU-E3AF25B14

Panasonic

R3,R4,R5

Resistor, Chip, Thk Film, 47k, 5%, 1/10W, 200ppm

ERJ-6GEYJ473V

Panasonic

R6,R9,R10,R11,R13,R14,

Zero Ohm Jumper, SMD 0805

ERJ-6GEYJ000V

Panasonic

R17,R19,R22,R23,R25,R27,

R29,R30,R33,R35,R36,R42

Resistor, Chip, Thk Film, 4.99K, 1%, 1/10W, 100ppm

ERJ-6ENF4991V

Panasonic

R12,R20,R45

Resistor, Chip, Thk Film, 10K, 5%, 1/10W, 200ppm

ERJ-6GEYJ103V

Panasonic

R15,R31

Resistor, Chip, Thk Film, 20, 5%, 1/4W, 200ppm

ERJ-14YJ200U

Panasonic

R16,R18,R32,R37

Resistor, Chip, Thk Film, 6.2, 5%, 1/4W, 200ppm

ERJ-14YJ6R2U

Panasonic

R24

Resistor, Chip, Thk Film, 470, 5%, 1/10W, 200ppm

ERJ-6GEYJ471V

Panasonic

R26

Resistor, Chip, Thk Film, 1Meg, 5%, 1/10W, 200ppm

ERJ-6GEYJ105V

Panasonic

R28

Resistor, Chip, Thk Film, 12.1k, 1%, 1/10W, 100ppm

ERJ-6ENF1212V

Panasonic

R34

Resistor, Chip, Thk Film, 49.9, 1%, 1/10W, 100ppm

ERJ-6ENF49R9V

Panasonic

R38,R39,R43

Resistor, Chip, Thk Film, 300, 5%, 1/10W, 200ppm

ERJ-6GEYJ301V

Panasonic

R40, R44

Resistor, Chip, Thk Film, 18k, 5%, 1/10W, 200ppm

ERJ-6GEYJ183V

Panasonic

R41

Resistor, Chip, Thk Film, 2.2k, 5%, 1/10W, 200ppm

ERJ-6GEYJ222V

Panasonic

R21

Resistor, Chip, Thk Film, 10, 5%, 1/4W, 200ppm

ERJ-14YJ100U

Panasonic

SW1

DIP Switch, 4-position, Raised-rocker, sealed

76SB04S

Grayhill

SW2

Switch, Momentary Tact, SMD, 230gf

B3S-1002

Omron

Digital Audio Interface Receiver IC

CS8415A-CS

Crystal/Cirrus logic

Microcontroller, 8-Bit, 8-Pin, w/ADC

PIC12C671-04/SM

Microchip

Toslink Light Receiving Unit

GP1F32R

Sharp

TinyLogic CMOS XOR gate

NC7SZ86M5

Fairchild

DDX Digital Processing ASIC

DDX2000

Apogee

DDX Power IC

DDX2100

Apogee

Regulator, Linear, 3.3V, .5A

LM2937IMP-3.3

NSC

Supervisor, 3.3V Econoreset

DS1233A-10/SM

Dallas

Switching Regulator, Step Down, 45V, 0.5A, Fixed +5V, 150KHz

LM2594M-5.0

NSC

Crystal, 11.2896 MHz, 50ppm, Fundamental Mode, SMD

MA-506-11.2896M-C2

EPSON

ALTERNATE

Crystal, 12.288 MHz, 50ppm, Fundamental Mode, SMD

MA-506-12.288M-C2

EPSON

Header, 2 pin, 1x2, .100 spacing, w/Locking ramp.

22-01-2027

Molex

________________ __ EB-2100x

Details are subject to change without notice.

FIGURE 12 - DDX EVALUATION AMPLIFIER ASSEMBLY DRAWING

Information furnished in this publication is believed to be accurate and reliable. However, Apogee Technology, Inc. assumes no
responsibility for its use, or for any infringements of patents or other rights of third parties that may result form its use. Specifications
in this publication are subject to change without notice. This publication supersedes and replaces all information previous supplied.

November 2001

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