WM8940
Pre-Production
Figure 6 Microphone Input PGA Circuit (switch positions shown are for differential mic
input)
REGISTER BIT
ADDRESS
R44
Input Control
LABEL
DEFAULT
DESCRIPTION
2
1
0
AUX2INPPGA
0
1
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.
MICN2INPPGA
MICP2INPPGA
Connect MICN to input PGA negative
terminal.
0=MICN not connected to input PGA
1=MICN connected to input PGA amplifier
negative terminal.
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
Table 2 Input Control
The input PGA is enabled by the IPPGAEN register bit.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R2
2
INPPGAEN
0
Input microphone PGA enable
0 = disabled
Power
Management 2
1 = enabled
Table 3 Input PGA Enable Control
Pre-Production, Rev 3.0, February 2007
18
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
