WM8940GEFL/V Wolfson Microelectronics, WM8940GEFL/V Datasheet - Page 22

• Manufacturer Part Number: WM8940GEFL/V
• Description: Audio CODECs Mono CODEC with Speaker Driver
• Manufacturer: Wolfson Microelectronics

Specifications of WM8940GEFL/V

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-24
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8940
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Table 6 Input BOOST Stage Control
Table 7 Input BOOST Stage Control
Table 8 Input BOOST Enable Control
MICROPHONE BIASING CIRCUIT
The Auxiliary amplifier path to the BOOST stage is controlled by the AUX2BOOSTVOL[2:0] register
bits.
Settings 001 through to 111 control the gain in 3dB steps from -12dB to +6dB.
The MICP path to the BOOST stage is controlled by the MICP2BOOSTVOL[2:0] register bits.
When MICP2BOOSTVOL=000 this input pin is completely disconnected from the BOOST stage.
Settings 001 through to 111 control the gain in 3dB steps from -12dB to +6dB.
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.
R45
Input PGA gain
control
R47
Input BOOST
control
R47
Input BOOST
control
R2
Power
management 2
REGISTER
REGISTER
REGISTER
ADDRESS
ADDRESS
ADDRESS
When AUX2BOOSTVOL=000 this path is completely disconnected from the BOOST stage.
6
8
6:4
2:0
4
BIT
BIT
BIT
MICP2BOOSTVOL
AUX2BOOSTVOL
BOOSTEN
INPPGAMUTE
PGABOOST
LABEL
LABEL
LABEL
When MBVSEL=0, MICBIAS=0.9*AVDD and when MBVSEL=1,
0
DEFAULT
1
0
DEFAULT
DEFAULT
000
000
Mute control for input PGA:
0=Input PGA not muted, normal operation
1=Input PGA muted (and disconnected from
the following input BOOST stage).
0 = PGA output has +0dB gain through
input BOOST stage.
1 = PGA output has +20dB gain through
input BOOST stage.
Input BOOST enable
0 = Boost stage OFF
1 = Boost stage ON
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
PD, Rev 4.2, April 2008
Production Data
22