wm8961 Wolfson Microelectronics plc, wm8961 Datasheet - Page 22

• 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

INPUT SIGNAL PATH
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WM8961
Figure 12 Analogue Input Stage
The WM8961 has a flexible stereo analogue input channel which can be configured as line inputs or
single-ended microphone inputs. The input signal path consists of an input volume control using a
Programmable Gain Amplifier (PGA), followed by an input boost stage. The output of the boost stage
drives a hi-fi stereo ADC. This is shown in Figure 12
The input PGAs and boost stage are enabled by the AINL and AINR register bits.
Table 4 Input PGA and Boost Enable Register Settings
INPUT PGA VOLUME CONTROLS
The gain of the microphone PGAs can be manually configured, or automatically controlled using the
ALC / Limiter. (Refer to section headed Automatic Level Control for more details).
The input PGA stage provide a general volume control for the LINPUT and RINPUT microphone
inputs and have a gain range from -23.25dB to +24dB in 0.75dB steps. The gain of the PGAs is
controlled by the register bits LINVOL[5:0] and RINVOL[5:0].
R25 (19h)
Power
Management
(1)
REGISTER
ADDRESS
5
4
BIT
AINL
AINR
LABEL
0
0
DEFAULT
Left channel input PGA and boost
stage enable
0 = PGA disabled, boost disabled
1 = PGA enabled boost enabled
Right channel input PGA and boost
stage enable
0 = PGA disabled, boost disabled
1 = PGA enabled boost enabled
DESCRIPTION
PP, August 2009, Rev 3.1
Pre-Production
22