STAC9750 Datasheet, PDF (37/73 Pages) Integrated Device Technology – VALUE-LINE TWO-CHANNEL AC’97 CODECS

STAC9750/9751
VALUE-LINE TWO-CHANNEL AC’97 CODECS
PC AUDIO
6.5.4.
Analog Mixer Input Gain Registers (Index 0Ch - 18h)
These registers control the gain/attenuation for each of the analog inputs. Each step corresponds to
approximately 1.5 dB. The MSB of the register is the mute bit. When this bit is set to 1 the level for
that channel is set at -∞ dB.
The default value for stereo registers is 8808h, corresponding to 0 dB gain with mute on.
Mute
0
0
0
Table 18. Analog Mixer Input Gain Register
Gx4…Gx0
0 0000
0 1000
1 1111
Function
+12 dB gain
0 dB gain
-34.5 dB gain
6.5.4.1. Phone Mixer Volume (0Ch)
Default: 8008h
D15
D14
D13
Mute
D7
D6
D5
Reserved
D12
D4
GN4
D11
Reserved
D3
GN3
D10
D2
GN2
D9
D1
GN1
D8
D0
GN0
6.5.4.2. Mic Mixer Volume (0Eh)
Default: 8008h
D15
Mute
D7
RSRVD
D14
D6
BOOST_EN
D13
D5
RSRVD
D12
D4
GN4
D11
Reserved
D3
GN3
D10
D2
GN2
D9
D1
GN1
D8
D0
GN0
Register 0Eh (Mic Volume Register) Bit D6 is the Mic boost enable. To select between 20dB or 30dB
Mic Boost, see register 6Eh, D2 in section 6.5.25; page 51.
6.5.4.3. Line In Mixer Volume (10h)
Default: 8808h
D15
Mute
D7
D14
D13
Reserved
D6
D5
Reserved
D12
GL4
D4
GR4
D11
GL3
D3
GR3
D10
GL2
D2
GR2
D9
GL1
D1
GR1
D8
GL0
D0
GR0
IDT™
VALUE-LINE TWO-CHANNEL AC’97 CODECS
37
STAC9750/9751
V 5.8 103106