wm8961 Wolfson Microelectronics plc, wm8961 Datasheet - Page 25

• Manufacturer Part Number: wm8961
• Description: Ultra-low Power Stereo Codec With 1w Stereo Class D Speaker Drivers And Ground Referenced Headphone Drivers
• Manufacturer: Wolfson Microelectronics plc

w
WM8961
Table 7 Microphone PGA Boost Control
The output of the boost stage drives the ADC.
MICROPHONE INPUT CONNECTION EXAMPLE AND MICROPHONE
BIASING
The input PGAs can be configured to use a single-ended input microphone. In the single ended
microphone input configuration the microphone signal can be input to LINPUT. An example of this is
shown in Figure 13 which also shows the microphone biasing.
Figure 13 Single Ended Microphone Configuration Example
MICROPHONE BIASING CIRCUIT
The MICBIAS output pin 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
MICBIAS=7/6×AVDD. The output can be enabled or disabled using the MICB control bit. (Note that
MBSEL=1 only allowed if MICVDD is greater than +2.40V)
Table 8 Microphone Bias Control
R32 (20h)
ADCL signal
path
R33 (21h)
ADCR signal
path
R25 (19h)
Power
management (1)
R48 (30h)
Additional Control
(4)
REGISTER
ADDRESS
REGISTER
MBSEL
ADDRESS
register
5:4
5:4
BIT
1
0
BIT
bit.
LMICBOOST
[1:0]
RMICBOOST
[1:0]
When
MICB
MBSEL
LABEL
LABEL
MBSEL=0,
0
1
DEFAULT
00
00
DEFAULT
MICBIAS=5/6×AVDD
Microphone Bias Enable
0 = OFF (high impedance output)
1 = ON
Microphone Bias Voltage Control
1 = 7/6 * AVDD
0 = 5/6 * AVDD
00 = +0dB
01 = +13dB
10 = +20dB
11 = +29dB
Right Channel Input PGA Boost Gain
00 = +0dB
01 = +13dB
10 = +20dB
11 = +29dB
Left Channel Input PGA Boost Gain
DESCRIPTION
DESCRIPTION
PP, August 2009, Rev 3.1
and
when
Pre-Production
MBSEL=1,
25