REV. A

–8–

SSM2160

APPLICATIONS INFORMATION

General

The SSM2160 is a 6-channel volume control intended for

multichannel audio applications. While dual-channel controls

sufficed for stereo applications, rapidly emerging home theater

surround sound and auto sound venues demand both 4-channel

and 6-channel high performance controls. Line level signals are fed

to the six high impedance inputs. The system microcontroller

sets the gain of the six channels via a 3-wire or 4-wire data bus.

In a home theater receiver, the outputs may be fed to the power

amplifiers or buffered and connected to pre-out/amp-in ports on

the rear panel. Refer to Figure 5 for a typical signal chain using

the SSM2160. The master control serves the volume control

function, and the channel control serves the balance function.

The 6-channel capability allows complete control of the front left,

front right, center, rear left, rear right, and sub-bass audio channels.

Power Supplies vs. Signal Levels

The SSM2160 can be operated from dual supplies from

±5V to

±10 V and from single supplies from +10 V to +20 V. To keep

power dissipation to a minimum, use the minimum power supply

voltages that will support the maximum input and output signal

levels. The peak-to-peak output signal level must not exceed 1/4

of the total power supply span, from V+ to V–. This restriction

applies for all conditions of input signal levels and gain/attenuation

settings. Table I shows supply voltages for several typical output

signal levels for the device. An on-chip buffered voltage divider

provides the correct analog common voltage for single-supply

applications.

Table I. Signal Levels vs. Power Supplies

Max Output,

Max Output

V rms (V p-p)

(dBu)

0.9 (2.5)

+1.3

10

±5

1.1 (3.0)

+3.0

12

±6

1.3 (3.7)

+4.5

15

±7.5

1.8 (5.0)

+7.3

20

±10

Dual Power Supplies

As shown in Figure 2, the AGND pin should be connected to

DGND, should always be connected to ground for either single-

or dual-supply configurations. Pins 1 and 12 should each have a

10

µF capacitor connected to ground, with a 0.1 µF capacitor

placed as close as possible to the SSM2160 to help reduce the

effects of high frequency power supply noise. When a switching

power supply is used, or if the power supply lines are noisy,

additional filtering of the power supply lines may be required.

+

1

2

V+

0.1 F

10 F

V–

10 F

12

13

DGND

V–

AGND

V+

SSM2160

+

0.1 F

Figure 2. Dual-Supply Configuration

Single Power Supply

When a single supply is used, it is necessary to connect AGND

voltage midway between the V+ and V– pins from a buffered

resistive divider. When supplying this reference to stages ahead

of the SSM2160 (to eliminate the need for input dc blocking

capacitors, for example), the use of an additional external

buffer, as shown in Figure 4, may be necessary to eliminate any

noise pickup.

+

+

V+

0.1 F

10 F

0.1 F

10 F

3

1

2

12

13

DGND

V–

AGND

V+

SSM2160

Figure 3. Single-Supply Configuration