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SSM2160/SSM2161

6 and 4 Channel, “Clickless” Serial Input

Balance/Master Volume Controls

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reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

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FEATURES

Digitally-Controlled “Clickless” Level Adjustment

SSM2160: Six Channels

SSM2161: Four Channels

Master Control has 128 1 dB Steps

Each Channel has 32 1 dB Steps

Step Sizes Can Be Changed Using External Resistors

High Gain Accuracy

100 dB Gain Range

Power On Mute

Excellent Audio Characteristics:

5 V)

5 V)

–80 dB Crosstalk (@ 1 kHz)

Single or Dual Supply Operation

APPLICATIONS

Dolby* Pro-Logic Master Volume/Balance Control

Home THX† Systems

DSP Soundfield Processors

Automotive Audio Systems

HDTV Audio Systems

REV. A

GENERAL DESCRIPTION

The SSM2160 and SSM2161 allow digital control of volume for

six and four channels, respectively, with a master level control.

“Clicking” normally encountered with resistor-ladder attenua-

tors is eliminated by using high performance Voltage Controlled

Amplifiers (VCAs) in the signal path. The VCA control ports

are driven by DACs with controlled output rate-of-change to in-

sure noiseless volume changes. Each channel is controlled by a

dedicated 5-bit DAC, providing 32 steps of adjustment. In addi-

tion, a master 7-bit DAC feeds every control port, with 128

steps. Therefore, a balance can be achieved among all channels

over a 32 step range, and the master control allows adjustment

over its entire range while maintaining the desired channel-to-

channel balance. Master and channel step sizes are nominally

1 dB; master step sizes can be reduced by an external resistor.

Approximately 80 dB of attenuation and up to 20 dB of gain is

possible. Upon power-up, the output is automatically muted.

The SSM2160/SSM2161 can operate from single supplies of

8 V to 14 V and dual supplies from

±4 V to ±7 V. An on-chip

buffered supply splitter provides an analog common for single-

supply applications.

*Dolby is a registered trademark of Dolby Laboratories Licensing

†Home THX is a registered trademark of Lucasfilm, Ltd.

FUNCTIONAL BLOCK DIAGRAM

SHIFT REGISTER

AND

ADDRESS

DECODER

POWER

SUPPLY AND

REFERENCE

7-BIT

MASTER

DAC

5-BIT

CHANNEL

DAC

VCA

TO ADDITIONAL CHANNELS

SSM-2160: SIX CHANNEL

SSM-2161: FOUR CHANNEL

AUDIO

CLK

DATA

LD

WRITE

V+

V–

ACOM

∑

OBSOLETE