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a

SSM2160/SSM2161

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1996

6- and 4-Channel, Serial Input

Master/Balance Volume Controls

FUNCTIONAL BLOCK DIAGRAM

POWER

SUPPLY AND

REFERENCE

GENERATOR

VCA

CH1 IN

CH1 OUT

CLK

DATA

LD

WRITE

V+

V–

∑

5-BIT

CHANNEL

DAC

VCA

CH2 IN

CH2 OUT

∑

5-BIT

CHANNEL

DAC

VCA

CH3 IN

CH3 OUT

∑

5-BIT

CHANNEL

DAC

VCA

CH4 IN

CH4 OUT

∑

5-BIT

CHANNEL

DAC

VCA

CH5 IN

CH5 OUT

∑

5-BIT

CHANNEL

DAC

VCA

CH6 IN

CH6 OUT

∑

5-BIT

CHANNEL

DAC

7-BIT

MASTER

DAC

SHIFT REGISTER

AND

ADDRESS

DECODER

STEP SIZE

ADJUST

CH SET

MSTR SET

MSTR OUT

FEATURES

Clickless Digitally Controlled Level Adjustment

SSM2160: Six Channels

SSM2161: Four Channels

7-Bit Master Control Gives 128 Levels of Attenuation

5-Bit Channel Controls Give 32 Levels of Gain

Master/Channel Step Size Set by External Resistors

100 dB Dynamic Range

Automatic Power On Mute

Excellent Audio Characteristics:

0.01% THD+N

0.001% IMD (SMPTE)

–90 dBu Noise Floor

–80 dB Channel Separation

90 dB SNR

Single and Dual Supply Operation

APPLICATIONS

Home Theater Receivers

Surround Sound Decoders

Circle Surround* and AC-3* Decoders

DSP Soundfield Processors

HDTV and Surround TV Audio Systems

Automotive Surround Sound Systems

Multiple Input Mixer Consoles and Amplifiers

GENERAL DESCRIPTION

The SSM2160 and SSM2161 allow digital control of volume of

six and four audio channels, respectively, with a master level

control and individual channel controls. Low distortion VCAs

(Voltage Controlled Amplifiers) are used in the signal path. By

using controlled rate-of-change drive to the VCAs, the “click-

ing” associated with switched resistive networks is eliminated in

the Master control. Each channel is controlled by a dedicated

5-bit DAC providing 32 levels of gain. A master 7-bit DAC

feeds every control port giving 128 levels of attenuation. Step

sizes are nominally 1 dB and can be changed by external

resistors. Channel balance is maintained over the entire master

control range. Upon power-up, all outputs are automatically

muted. A three- or four-wire serial data bus enables interfacing

with most popular microcontrollers. Windows

* software and an

evaluation board for controlling the SSM2160 are available.

The SSM2160 can be operated from single supplies of +10 V to

+20 V or dual supplies from

±5 V to ±10 V. The SSM2161 can

be operated from single supplies of +8.5 V to +20 V (for

automotive applications) or dual supplies from

±4.25 V to

±10 V. An on-chip reference provides the correct analog

common voltage for single supply applications. Both models

come in P-DIP and SO packages. See the Ordering Guide for

more details.

*Circle Surround is a registered trademark of Rocktron Corporation.

AC-3 is a registered trademark of Dolby Labs, Inc. Windows is a regis-

tered trademark of Microsoft Corp.