STA333IS datasheet(31/43 Pages) STMICROELECTRONICS

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STA333IS

5.2.2

Master volume register (addr 0x07)

5.2.3

Channel volume (addr 0x08, 0x09)

Volume setting

The volume structure of the STA333IS consists of individual volume registers for each

channel and a master volume register that provides an offset to each channel’s 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, will mute all channels at once, whereas the individual

channel mutes (CxM) mute 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 (about 96 kHz). A hard mute can be

obtained by commanding a value of all 1’s (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 F)

on a per-channel basis as this creates the smoothest possible volume transitions. When

ZCE = 0, volume updates will occur immediately.

MV7

MV6

MV5

MV4

MV3

MV2

MV1

MV0

C1V7

C1V6

C1V5

C1V4

C1V3

C1V2

C1V1

C1V0

C2V7

C2V6

C2V5

C2V4

C2V3

C2V2

C2V1

C2V0

Table 41. Master volume offset as a function of MV

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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