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SSM2160

6-Channel, Serial Input

Master/Balance Volume Controls

FEATURES

Clickless Digitally Controlled Level Adjustment

SSM2160: 6 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

DSP Soundfield™ Processors

HDTV and Surround TV Audio Systems

Automotive Surround Sound Systems

Multiple Input Mixer Consoles and Amplifiers

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

SSM2160

GENERAL DESCRIPTION

The SSM2160 allows digital control of volume of six audio

channels, 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 “clicking” 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 automati-

cally muted. A 3-wire or 4-wire serial data bus enables interfacing

with most popular microcontrollers. Windows

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. An on-chip reference

provides the correct analog common voltage for single-supply

applications. The SSM2160 comes in a SOIC package; see the

Ordering Guide for details.