WM8941
Pre Production
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R47
6:4 MICP2BOOSTVOL 000
Controls the MICP pin to the input boost
stage (NB, when using this path set
MICP2INPPGA=0):
Input BOOST
control
000=Path disabled (disconnected)
001=-12dB gain through boost stage
010=-9dB gain through boost stage
…
111=+6dB gain through boost stage
2:0 AUX2BOOSTVOL
000
Controls the auxiliary amplifier to the input
boost stage:
000=Path disabled (disconnected)
001=-12dB gain through boost stage
010=-9dB gain through boost stage
…
111=+6dB gain through boost stage
Table 7 Input BOOST Stage Control
The BOOST stage is enabled under control of the BOOSTEN register bit.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Input BOOST enable
R2
4
BOOSTEN
0
Power
management 2
0 = Boost stage OFF
1 = Boost stage ON
Table 8 Input BOOST Enable Control
MICROPHONE BIASING CIRCUIT
The MICBIAS output provides a low noise reference voltage suitable for biasing electret type
microphones and the associated external resistor biasing network. Refer to the Applications
Information section for recommended external components. The MICBIAS voltage can be altered via
the MBVSEL register bit.
When MBVSEL=0, MICBIAS=0.9*AVDD and when MBVSEL=1,
MICBIAS=0.65*AVDD. The output can be enabled or disabled using the MICBEN control bit.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Microphone Bias Enable
R1
4
MICBEN
0
Power
management 1
0 = OFF (high impedance output)
1 = ON
Table 9 Microphone Bias Enable
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R44
Input Control
8
MBVSEL
0
Microphone Bias Voltage Control
0 = 0.9 * AVDD
1 = 0.65 * AVDD
Table 10 Microphone Bias Voltage Control
PP, Rev 3.3, December 2007
24
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
