WM1811A datasheet(42/328 Pages) WOLFSON

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WM1811A

Production Data

PD, November 2013, Rev 4.1

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

MICB2_MODE

Microphone Bias 2 Mode

0 = Regulator mode

1 = Bypass mode

3:1

MICB2_LVL [2:0]

100

Microphone Bias 2 Voltage Control

(when MICB2_MODE = 0)

000 = 1.5V

001 = 1.8V

010 = 1.9V

011 = 2.0V

100 = 2.2V

101 = 2.4V

110 = 2.5V

111 = 2.6V

MICB2_DISCH

Microphone Bias 2 Discharge

0 = MICBIAS2 floating when disabled

1 = MICBIAS2 discharged when disabled

Table 1 Microphone Bias Control

Note that the maximum source current capability for MICBIAS1 and MICBIAS2 is 2.4mA each in

Regulator mode. The external biasing resistance must be large enough to limit each MICBIAS current

to 2.4mA across the full microphone impedance range. The maximum source current for MICBIAS1

and MICBIAS2 is 3.6mA each in Bypass mode, as described in the “Electrical Characteristics”.

MICROPHONE ACCESSORY DETECT

The WM1811A provides a microphone detection function, which uses impedance measurement to

detect one or more different external accessory connections. This feature is described in the “External

Accessory Detection” section.

LINE AND VOICE CODEC INPUTS

All eight analogue input pins may be used as line inputs. Each line input has different signal path

options, providing flexibility, high performance and low power consumption for many different usage

modes.

IN1LN and IN1RN can operate as single-ended line inputs to the input PGAs IN1L and IN1R

respectively. These inputs provide a high gain path if required for low input signal levels.

IN2LN and IN2RN can operate as single-ended line inputs to the input PGAs IN2L and IN2R

respectively, providing further high gain signal paths. These pins can also be connected to either of

the output mixers MIXOUTL and MIXOUTR.

IN1LP and IN1RP can operate as single-ended line inputs to the input mixers MIXINL and MIXINR, or

to the speaker mixers SPKMIXL and SPKMIXR. These signal paths enable power consumption to be

reduced, by allowing the input PGAs and other circuits to be disabled if not required.

IN2LP/VRXN and IN2RP/VRXP can operate in three different ways:



Mono differential ’RXVOICE’ input (e.g. from an external voice CODEC) to the input mixers

MIXINL and MIXINR.



Single-ended line inputs to either of the output mixers MIXOUTL and MIXOUTR.

Signal path configuration to the input PGAs and input mixers is detailed later in this section. Signal

path configuration to the output mixers and speaker mixers is described in “Analogue Output Signal

Path”.

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