WM9714CLGEFLSLASHV datasheet(46/120 Pages) CIRRUS

46 / 120 page

WM9714L

Rev 4.0

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 21.

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.

MICBIAS

Vmi

MICB

MIC2B

MPB

MPBEN

Vmi

MICA

MIC2A

MPA

MPAEN

Vmi

MICCM

WM9714L

MIC

Figure 21 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

“Applications Information”

for recommended external components. The MICBIAS voltage can be altered via MBVOL in register

22h. When MBVOL=0, MICBIAS=0.9*AVDD and when MBVOL=1, MICBIAS=0.75*AVDD.

The microphone bias is driven to a dedicated MICBIAS pin 28 and is enabled by MPOP1EN in

22h.

When not in use the microphone bias can be powered down using the Powerdown register bit

MICBIAS (register 3Eh, bit 14).

WM9714CLGEFL/V Datasheet(PDF) 46 Page - Cirrus Logic