WM8753L datasheet(26/87 Pages) WOLFSON

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WM8753L

AI Rev 3.1 June 2004

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R2 (02h)

ADC control

[6:5]

ADCPOL[1:0]

00 = Polarity not inverted

01 = L polarity invert

10 = R polarity invert

11 = L and R polarity invert

Table 11 ADC Polarity Control

SINGLE ENDED OPERATION

It is possible to connect up to three microphones single endedly.

Microphone1 is connected to the

MIC1 input , microphone2 to the MIC2 input, microphone3 to the MIC2N input and MIC1N is

connected to Vref. The gains, MIC1BOOST and MIC2BOOST, should be set to be identical and

micamp2 must be disabled. Any of the three microphones can then be selected as the output from

micamp1 using MICSEL.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R51 (33h)

Mic Select

[7:6]

MICSEL[1:0]

Microphone selected

00 : MIC1

01 : MIC2

10 : MIC3

11 : unused

Table 12 MIC Select Control

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

the MBVSEL register bit.

When MBVSEL=0, MICBIAS=0.9*AVDD and when MBVSEL=1,

MICBIAS=0.75*AVDD. The output can be enabled or disabled using the MICB control bit (see also

the “Power Management” section).

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R20 (14h)

Power

Management (1)

MICB

Microphone Bias Enable

0 = OFF (high impedance output)

1 = ON

Table 13 Microphone Bias Control

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R51 (33h)

Mic bias comp

control

MBVSEL

Microphone Bias Voltage Control

0 = 0.9 * AVDD

1 = 0.75 * AVDD

Table 14 Microphone Bias Voltage Control

The internal MICBIAS circuitry is shown in Figure 8. Note that the maximum source current capability

for MICBIAS is 3mA. The external biasing resistors therefore must be large enough to limit the

MICBIAS current to 3mA.

WM8753L Datasheet(PDF) 26 Page - Wolfson Microelectronics plc

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