WM9713 datasheet(43/111 Pages) WOLFSON

43 / 111 page

Preliminary Technical Data

WM9713L

PTD, March 2004, Rev 2.2

SINGLE MIC OPERATION

Up to three microphones can be connected in a single-ended configuration. Any one of the three

MICs can be selected as the input to MPA using MPASEL[1:0] (Register 22h, bits 13:12). Only the

microphone on MIC2B can be selected to MPB. Note that MPABST always sets the gain for the

selected MPA input microphone. If MIC2B is the selected input for MPA it is recommended that MPB

is disabled.

DUAL MIC OPERATION

Up to two microphones can be connected in a dual differential configuration. This is suitable for

stereo microphone or noise cancellation applications. Mic1 is connected between the MIC2A and

MICCM inputs and mic2 is connected between the MIC2B and MICCM inputs as shown in Figure 13.

Additionally, another microphone can be supported on MIC1 selected through the MPA input mux.

Note that the microphones can be connected in a single-ended configuration.

Figure 13 Dual Microphone Configuration

MICROPHONE BIASING CIRCUIT

The MICBIAS output 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

MBVOL

22h.

When

MBVOL=0,

MICBIAS=0.9*AVDD

and

when MBVOL=1,

MICBIAS=0.75*AVDD.

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