wm8952 Wolfson Microelectronics plc, wm8952 Datasheet - Page 15

• Manufacturer Part Number: wm8952
• Description: Mono Adc With Microphone Pre-amplifier
• Manufacturer: Wolfson Microelectronics plc

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INPUT SIGNAL PATH
MICROPHONE INPUTS
The WM8952 can accommodate a variety of microphone configurations including single ended and
differential inputs. The inputs through the MICN, MICP and optionally AUX pins are amplified through
the input PGA as shown in Figure 6 .
A pseudo differential input is the preferential configuration where the positive terminal of the input
PGA is connected to the MICP input pin by setting MICP2INPPGA=1. The microphone ground
should then be connected to MICN (when MICN2INPPGA=1) or optionally to AUX (when
AUX2INPPGA=1) input pins.
Alternatively a single ended microphone can be connected to the MICN input with MICN2INPPGA set
to 1. The non-inverting terminal of the input PGA should be connected internally to VMID by setting
MICP2INPPGA to 0.
In pseudo-differential mode the larger signal should be input to MICP and the smaller (e.g. noisy
ground connections) should be input to MICN.
Figure 6 Microphone Input PGA Circuit (switch positions shown are for differential mic
input)
POWER CONTROL
The design of the WM8952 has given much attention to power consumption without compromising
performance. It operates at low supply voltages, and includes the facility to power off any unused
parts of the circuitry under software control.
As a power saving measure, ADC logic in the DSP core is held in its last enabled state when the
ADC is disabled. In order to prevent pops and clicks on restart due to residual data in the filters, the
master clock must remain for at least 64 input samples after the ADC has been disabled.
The WM8952 has 3 flexible analogue inputs: two microphone inputs, and an auxiliary input. These
inputs can be used in a variety of ways. The input signal path before the ADC has a flexible PGA
block which then feeds into a gain boost/mixer stage.
PP, Rev 3.0, December 2008
WM8952
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