WM8753LEBSLASHV datasheet(27/87 Pages) WOLFSON

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WM8753L

Advanced Information

AI Rev 3.1 June 2004

AGND

MBVSEL=0

MICBIAS

= 1.8 x VMID

= 0.9 X AVDD

VMID

internal

resistor

internal

resistor

MBVSEL=1

MICBIAS

= 1.5 x VMID

= 0.75 X AVDD

Figure 8 Microphone Bias Schematic

MICBIAS CURRENT DETECT

The WM8753L includes a microphone bias current detect circuit which allows the user to set

thresholds for the microphone bias current, above which an interrupt will be triggered. There are two

separate interrupt bits, MICDET to allow the user to e.g. distinguish between one or two microphones

connected to the WM8753L, and MICSHT to detect a shorted microphone (mic button press). The

thresholds for the microphone bias current are set by MBTHRESH[2:0], for MICDET, and

MBSCTHRESH[1:0] for MICSHT. Thresholds for each code are shown in Table 15. The circuit is

enabled by setting MBCEN.

See the GPIO and Interrupt Controller sections for details on the interrupt and status readback for the

microphone bias current detect.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

5:4

MBSCTHRESH

Microphone Bias, Shorted Current

Threshold Select

00: 500uA

01: 1000uA

10: 1600uA

11: 2300uA

These values are for 3.3V supply and

scale with supply voltage.

3:1

MBTHRESH

000

Microphone Bias, Current Threshold

Select

000:250uA

001:410uA

….160uA steps up to

111:1370uA

These values are for 3.3V supply and

scale with supply voltage.

R51 (33h)

MBCEN

Mic Bias Current Comparator Circuit

enable

0 : Comparator disabled

1 : Comparator enabled

Table 15 Mic Bias Current Comparator Circuit Control

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