WM8980CGEFL/RV WOLFSON [Wolfson Microelectronics plc], WM8980CGEFL/RV Datasheet - Page 30

• Manufacturer Part Number: WM8980CGEFL/RV
• Description: Stereo CODEC with Speaker Driver and Video Buffer
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

WM8980
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Table 9 Input BOOST Enable Control
MICROPHONE BIASING CIRCUIT
Table 10 Microphone Bias Enable Control
Table 11 Microphone Bias Voltage Control
Figure 15 Microphone Bias Schematic
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. 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.
The internal MICBIAS circuitry is shown in Figure 15. Note that the maximum source current
capability for MICBIAS is 3mA. The external biasing resistors therefore must be large enough to limit
the MICBIAS current to 3mA.
R2
Power
management
2
R1
Power
management 1
R44
Input control
REGISTER
REGISTER
ADDRESS
ADDRESS
REGISTER
ADDRESS
4
5
8
BIT
BIT
4
BIT
BOOSTENL
BOOSTENR
MBVSEL
LABEL
LABEL
MICBEN
LABEL
0
DEFAULT
0
DEFAULT
0
0
DEFAULT
Microphone Bias Voltage Control
0 = 0.9 * AVDD
1 = 0.65 * AVDD
Microphone Bias Enable
0 = OFF (high impedance output)
1 = ON
Left channel Input BOOST enable
0 = Boost stage OFF
1 = Boost stage ON
Right channel Input BOOST enable
0 = Boost stage OFF
1 = Boost stage ON
DESCRIPTION
DESCRIPTION
DESCRIPTION
PP, Rev 3.8, May 2012
Pre-Production
30