WM8959
Pre-Production
INPUT PGA CONFIGURATION
Each of the four Input PGAs can be configured in single-ended or pseudo-differential mode.
Single-ended microphone operation of an Input PGA is selected by connecting the input source to
the inverting PGA input. The non-inverting PGA input must be connected to VMID by setting the
appropriate register bits.
For pseudo-differential microphone operation, the inverting and non-inverting PGA inputs are both
connected to the input source and not to VMID.
For any line input or other connection not using the Input PGA, the appropriate PGA input should be
disconnected from the external pin and connected to VMID.
Register bits LMN1, LMP2, LMN3, LMP4, RMN1, RMP2, RMN3 and RMP4 control connection of the
PGA inputs to the device pins as shown in Table 4. The maximum available attenuation on any of
these input paths is achieved using these bits to disable the input path to the applicable PGA.
When not enabled as analogue inputs or as General Purpose inputs, the input pins can be biased to
VREF via a 1kΩ resistor by setting the BUFIOEN bit. See “Pop Suppression Control” for details.
REGISTER
ADDRESS
BIT
LABEL
LMP4
DEFAULT
DESCRIPTION
R40 (28h)
7
0b
LIN34 PGA Non-Inverting Input Select
0 = LIN4 not connected to PGA
1 = LIN4 connected to PGA
6
5
4
3
2
1
0
LMN3
LMP2
LMN1
RMP4
RMN3
RMP2
RMN1
0b
0b
0b
0b
0b
0b
0b
LIN34 PGA Inverting Input Select
0 = LIN3 not connected to PGA
1 = LIN3 connected to PGA
LIN12 PGA Non-Inverting Input Select
0 = LIN2 not connected to PGA
1 = LIN2 connected to PGA
LIN12 PGA Inverting Input Select
0 = LIN1 not connected to PGA
1 = LIN1 connected to PGA
RIN34 PGA Non-Inverting Input Select
0 = RIN4 not connected to PGA
1 = RIN4 connected to PGA
RIN34 PGA Inverting Input Select
0 = RIN3 not connected to PGA
1 = RIN3 connected to PGA
RIN12 PGA Non-Inverting Input Select
0 = RIN2 not connected to PGA
1 = RIN2 connected to PGA
RIN12 PGA Inverting Input Select
0 = RIN1 not connected to PGA
1 = RIN1 connected to PGA
Table 4 Input PGA Configuration
PP, May 2008, Rev 3.1
40
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
