SSM2163

REV. 0

–11–

SSM2163 power supply connections

Power Supplies and Decoupling

The SSM2163 operates from either single or dual (split) power

supplies. In either case, proper supply decoupling is important

to maximize audio performance.

To reduce noise, separate pins are provided for the digital and

analog power supply connections. These pins should be

SSM2163 package as possible (Figures 22a, 22b, 22c, power

supply connections).

Single Supply Operation

The SSM2163 will operate with a single power supply of +5 V

to +14 V. Single supply operation simplifies design and reduces

system cost in multimedia applications, battery powered

systems, and similar designs. The SSM2163 provides about

2 dB of headroom (to 1% THD+N) when operating from a

single +5 V supply.

The key to operating from a single supply is to reference all

analog common connections to a voltage midway between the

supply and ground. To simplify single supply operation, the

SSM2163 provides a buffered pseudo-ground reference (ACOM)

on Pin 13. This reference, shown in Figure 23, provides a low

impedance output at approximately one half of the supply

voltage. Connect Analog Ground (Pin 17) to the ACOM output

(Pin 13) for single supply operation. To minimize noise caused

by modulation of the pseudo-ground, Pin 13 should be bypassed to

power supply ground with 0.1

µF and 10 µF capacitors.

stored in the attenuator control registers. To re-enable the

system after a mute, use the address byte to turn on the desired

mixer channel. The selected channel will then operate with the

previously set attenuator value.

Serial Data Input Format

As previously mentioned, data is written to the SSM2163 in two

8-bit bytes. The serial data format is shown in the Address and

Data Decoding Truth Table, Figure 3. The first byte sent contains

the channel address and the Left/Right output mixer control bits.

The address byte is identified by the MSB being high.

The second byte contains the data (i.e., the attenuator value).

The six LSBs of this byte set the attenuation level, from 0 dB to

–63 dB. The MSB of the data byte must be a logic zero.

The standard format for data sent to the SSM2163 is an address

byte followed by a data (attenuator level) byte. In some cases,

however, only one byte needs to be sent. For example,

attenuation levels are not affected by the MUTE input. To turn

a muted channel on, simply send an address byte with the Left

or Right mixer bit set. The addressed channel will immediately

be enabled, using the previously-set attenuation level.

Furthermore, once a channel is addressed the attenuation level

can be varied by sending additional data bytes. For example,

fading a channel can be accomplished by simply incrementing

the data value sent to the SSM2163.

Serial Data Output

The MSB of the shift register is available on the serial DATA

OUTPUT pin. This output can be connected to the input of

another SSM2163 to permit “daisy-chain” operation. See

Figure 26 for a typical application. The DATA OUTPUT pin

Logic Levels

All of the SSM2163 logic inputs have TTL and CMOS

compatible thresholds. However, the allowable voltage range

(NC)

10

17

12

1

AGND

DGND

V+

EXTERNAL

REFERENCE

0.1

µF

10

µF

+

V

CC

V

EE

ACOM

2

V

SS

V

DD

4

Figure 22c. Single Supply Using External

Reference

10

17

12

1

V

CC

AGND

V

EE

DGND

V+

VREF

OUT

13

0.1

µF

10

µF

+

0.1

µF

10

µF

+

ACOM

2

V

SS

V

DD

4

Figure 22b. Single Supply

10

17

12

1

AGND

ACOM

DGND

V+

V–

(NC)

0.1

µF

10

µF +

0.1

µF

10

µF

V

CC

V

EE

4

2

V

SS

V

DD

Figure 22a. Dual Supply