sta339bw STMicroelectronics, sta339bw Datasheet - Page 46

• Manufacturer Part Number: sta339bw
• Description: 2.1-channel High-efficiency Digital Audio System
• Manufacturer: STMicroelectronics

Register description
6.7.5
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Channel 3 / line output volume
The Volume structure of the STA339BW consists of individual volume registers for each
channel and a master volume register that provides an offset to each channels 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
mutes (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
(addr 0x04) on page
volume transitions. When ZCE = 0, volume updates occur immediately.
Table 53.
Table 54.
00000000 (0x00)
00000001 (0x01)
00000010 (0x02)
…
01001100 (0x4C)
…
11111110 (0xFE)
11111111 (0xFF)
00000000 (0x00)
00000001 (0x01)
00000010 (0x02)
…
01011111 (0x5F)
01100000 (0x60)
C3V7
D7
0
CxV[7:0]
MV[7:0]
Master volume offset as a function of MV[7:0]
Channel volume as a function of CxV[7:0]
C3V6
D6
1
36) on a per channel basis as this creates the smoothest possible
C3V5
D5
1
0 dB
-0.5 dB
-1 dB
…
-38 dB
…
-127.5 dB
Hard master mute
+48 dB
+47.5 dB
+47 dB
…
+0.5 dB
0 dB
Doc ID 15251 Rev 4
C3V4
D4
0
Volume offset from channel value
C3V3
D3
0
Volume
C3V2
D2
0
(Configuration register E
C3V1
D1
0
STA339BW
C3V0
D0
0