CS4205
5.7
Microphone Volume Register (Index 0Eh)
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Mute
0
0
0
0
0
0
0
0
20dB
0
GN4 GN3 GN2 GN1 GN0
Mute
Microphone Mute. Setting this bit mutes the MIC1 or MIC2 signal. The selection of the MIC1
or MIC2 input pin is controlled by the MS bit in the General Purpose Register (Index 20h).
20dB
Microphone 20 dB Boost. When ‘set’, the 20dB bit enables the +20 dB microphone boost
block. In combination with the 10dB boost bit in the Misc. Crystal Control Register (Index 60h)
this bit allows for variable boost from 0 dB to +30 dB in steps of 10 dB. Table 6 summarizes
this behavior.
GN[4:0]
Default
Microphone Volume Control. The GN[4:0] bits are used to control the gain level of the Micro-
phone input source to the Input Mixer. Each step corresponds to 1.5 dB gain adjustment, with
01000 = 0 dB. The total range is +12 dB to -34.5 dB gain. See Table 6 for further details.
8008h. This value corresponds to 0 dB gain and Mute ‘set’.
Gain Level
GN4 - GN0
10dB = 0, 10dB = 1, 10dB = 0, 10dB = 1,
20dB = 0
+12.0 dB
+10.5 dB
…
20dB = 0
+22.0 dB
+20.5 dB
...
20dB = 1
+32.0 dB
+30.5 dB
...
20dB = 1
+42.0 dB
+40.5 dB
...
00000
00001
…
00111
01000
01001
…
+1.5 dB
0.0 dB
-1.5 dB
…
+11.5 dB
+10.0 dB
+8.5 dB
...
+21.5 dB
+20.0 dB
+18.5 dB
...
+31.5 dB
+30.0 dB
+28.5 dB
...
11111
-34.5 dB
-24.5 dB
-14.5 dB
-4.5 dB
Table 6. Microphone Input Gain Values
30
DS489PP4
CIRRUS [ CIRRUS LOGIC ]
