WM8976CGEFLSLASHV datasheet(22/114 Pages) WOLFSON

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WM8976

Production Data

PD, Rev 4.5, November 2011

selectable ‘application filters’ after the ADC provide for features such as ‘wind noise’ reduction, or

mechanical noise reducing filters.

Digital still camera recording; Support for digital recording is similar to the camcorder case. However,

additionally if the DSC supports MP3 playback, and perhaps recording, the ability of the ADC to

support full 48ks/s high quality recording increases device flexibility.

AUXILIARY ANALOGUE INPUTS

An analogue stereo FM tuner or other auxiliary analogue input can be connected to the AUX inputs of

WM8976, and the stereo signal listened to via headphones.

INPUT SIGNAL PATH

The WM8976 has flexible analogue inputs. An input PGA stage is followed by a boost/mix stage

which drives into the hi-fi ADC. The input path has three input pins which can be configured in a

variety of ways to accommodate single-ended or differential microphones. There is an auxiliary input

pin which can be fed into to the input boost/mix stage as well as driving into the output path. A bypass

path exists from the output of the boost/mix stage into the output left/right mixers.

MICROPHONE INPUTS

The WM8976 can accommodate a variety of microphone configurations including single ended and

differential inputs. The inputs to the differential input PGA are LIN, LIP and L2.

In single-ended microphone input configuration the microphone signal should be input to LIN and the

internal NOR gate configured to clamp the non-inverting input of the input PGA to VMID.

In differential mode the larger signal should be input to LIP and the smaller (e.g. noisy ground

connections) should be input to LIN.

Figure 10 Microphone Input PGA Circuit

The input PGA is enabled by the IPPGAENL register bits.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Power

Management

INPPGAENL

Input PGA enable

0 = disabled

1 = enabled

Table 4 Input PGA Enable Register Settings

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