Production Data
WM8352
13.4.5 MICROPHONE BIASING
The WM8352 provides a programmable, low-noise bias voltage for condenser electret microphones
on the MICBIAS pin.
ADDRESS
R8 (08h)
BIT
LABEL
DEFAULT
DESCRIPTION
Microphone bias enable
4
MICB_ENA
0
Power Mgmt 1
R74 (4Ah)
0 = OFF (high impedance output)
1 = ON
15
14
MICB_ENA
MICB_SEL
Mic Bias
Control
0
Microphone bias voltage control:
0 = 0.9 * AVDD
1 = 0.75 * AVDD
Note: MICB_ENA can be accessed through R8 or through R74. Reading from or writing to either
register location has the same effect.
Table 23 Controlling the Microphone Bias Voltage
13.4.6 AUXILIARY INPUTS (IN3L AND IN3R)
The WM8352 provides two additional analogue input pins, IN3L and IN3R, for line-level audio or
“beep” signals. Each pin has a simple input buffer whose output signal can be digitised in the audio
ADC and/or mixed into the output signal path. The Right input IN3R may also be connected to the
Output Beep Mixer, for output on OUT2R (see Table 43). The input buffers have a nominal default
gain of -1 (0dB).
IN3L_SHORT, R73[6]
20k
IN3L
To:
-
+
20k
Left Input Mixer,
Left Output Mixer
Vmid
IN3R_SHORT, R73[14]
20k
IN3R
To:
-
+
20k
Right Input Mixer,
Right Output Mixer,
Output Beep Mixer
Vmid
Figure 38 Auxiliary Input Buffers
PD, February 2011, Rev 4.4
67
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
