Cirrus Logic WM8940 Manual page 21

Rev 4.4
Output from
AUX amp
AUX2INPPGA
R44[2]
MICN2INPPGA
R44[1]
MICN
MICP2INPPGA
R44[0]
MICP
Figure 6 Microphone Input PGA Circuit (switch positions shown are for differential mic input)
REGISTER BIT LABEL
ADDRESS
R44 2 AUX2INPPGA
Input Control
1 MICN2INPPGA
0 MICP2INPPGA
Table 2 Input Control
The input PGA is enabled by the IPPGAEN register bit.
REGISTER BIT
ADDRESS
R2 2 INPPGAEN
Power
Management 2
Table 3 Input PGA Enable Control
Gain=-12 to +35.25dB
INPPGAVOL
R45[5:0]
VMID
DEFAULT
0 Select AUX amplifier output as input PGA
signal source.
0=AUX not connected to input PGA
1=AUX connected to input PGA amplifier
negative terminal.
1 Connect MICN to input PGA negative
terminal.
0=MICN not connected to input PGA
1=MICN connected to input PGA amplifier
negative terminal.
0 Connect input PGA amplifier positive
terminal to MICP or VMID.
0 = input PGA amplifier positive terminal
connected to VMID
1 = input PGA amplifier positive terminal
connected to MICP through variable resistor
string
LABEL DEFAULT
0 Input microphone PGA enable
0 = disabled
1 = enabled
WM8940
To input
BOOST/mix
stage
DESCRIPTION
DESCRIPTION
21