CS4299 Datasheet, PDF (23/52 Pages) Cirrus Logic – CrystalClear SoundFusion Audio Codec 97

CS4299
4.7 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
GN[4:0]
20dB
Default
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).
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 3 for further details.
Microphone 20 dB Boost. When ‘set’, the 20dB bit enables the +20 dB microphone boost block.
This bit allows for variable boost of 0 dB or +20 dB. Table 3 summarizes this behavior.
8008h. This value corresponds to 0 dB gain and Mute ‘set’.
GN[4:0]
00000
00001
…
00111
01000
01001
…
11111
Gain Level
20dB = 0 20dB = 1
+12.0 dB +32.0 dB
+10.5 dB +30.5 dB
…
...
+1.5 dB +21.5 dB
0.0 dB +20.0 dB
-1.5 dB +18.5 dB
…
...
-34.5 dB -14.5 dB
Table 3. Microphone Input Gain Values
23