STA350B datasheet(56/94 Pages) STMICROELECTRONICS

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STA350B, STA350BW

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DocID018572 Rev 7

8.7.4

Channel 2 volume

8.7.5

Channel 3 / line output volume

The volume structure of the STA350Bx consists of individual volume registers for each

channel and a master volume register that provides an offset to each channel volume

setting. The individual channel volumes are adjustable in 0.5 dB steps from +48 dB

to -80 dB.

As an example if C3V = 0x00 or +48 dB and MV = 0x18 or -12 dB, then the total gain for

channel 3 = +36 dB.

The master mute, when set to 1, mutes all channels at once, whereas the individual channel

mute (CxM) mutes only that channel. Both the master mute and the channel mutes provide

a “soft mute” with the volume ramping down to mute in 4096 samples from the maximum

volume setting at the internal processing rate (approximately 96 kHz).

A “hard (instantaneous) mute” can be obtained by programming a value of 0xFF (255) to

any channel volume register or the master volume register. When volume offsets are

provided via the master volume register, any channel whose total volume is less than -80 dB

is muted.

All changes in volume take place at zero-crossings when ZCE = 1 (Configuration register E

(addr 0x04)) on a per channel basis as this creates the smoothest possible volume

transitions. When ZCE = 0, volume updates occur immediately.

C2V7

C2V6

C2V5

C2V4

C2V3

C2V2

C2V1

C2V0

0110

0000

C3V7

C3V6

C3V5

C3V4

C3V3

C3V2

C3V1

C3V0

0110

0000

Table 52. Master volume offset as a function of MV[7:0]

MV[7:0]

Volume offset from channel value

00000000 (0x00)

0 dB

00000001 (0x01)

-0.5 dB

00000010 (0x02)

-1 dB

……

01001100 (0x4C)

-38 dB

……

11111110 (0xFE)

-127.5 dB

11111111 (0xFF)

Hard master mute

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