wm8941 Wolfson Microelectronics plc, wm8941 Datasheet - Page 23

• Manufacturer Part Number: wm8941
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

Production Data
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Table 7 Input BOOST Stage Control
Table 8 Input BOOST Enable Control
MICROPHONE BIASING CIRCUIT
Table 9 Microphone Bias Enable
Table 10 Microphone Bias Voltage Control
The BOOST stage is enabled under control of the BOOSTEN register bit.
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.
MICBIAS=0.65*AVDD. The output can be enabled or disabled using the MICBEN control bit.
R47
Input BOOST
control
R2
Power
management 2
R1
Power
management 1
R44
Input Control
REGISTER
REGISTER
ADDRESS
ADDRESS
REGISTER
REGISTER
ADDRESS
ADDRESS
6:4
2:0
4
BIT
BIT
4
8
BIT
BIT
MICP2BOOSTVOL
AUX2BOOSTVOL
BOOSTEN
LABEL
MICBEN
MBVSEL
LABEL
When MBVSEL=0, MICBIAS=0.9*AVDD and when MBVSEL=1,
LABEL
LABEL
0
0
0
DEFAULT
DEFAULT
DEFAULT
000
DEFAULT
000
Input BOOST enable
0 = Boost stage OFF
1 = Boost stage ON
Microphone Bias Enable
0 = OFF (high impedance output)
1 = ON
Microphone Bias Voltage Control
0 = 0.9 * AVDD
1 = 0.65 * AVDD
Controls the MICP pin to the input boost
stage (NB, when using this path set
MICP2INPPGA=0):
000=Path disabled (disconnected)
001=-12dB gain through boost stage
010=-9dB gain through boost stage
…
111=+6dB gain through boost stage
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
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD, Rev 4.0, August 2008
WM8941
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