WM9712CLGEFLSLASHV datasheet(75/78 Pages) WOLFSON

75 / 78 page

Production Data

WM9712L

PD, Rev 4.6, November 2011

JACK INSERT DETECTION

The circuit diagram below shows how to detect when a headphone or headset has been plugged into

the headphone socket. It generates an interrupt, instructing the controller to enable HPOUTL and

HPOUTR and disable OUT3.

switch closes

on insertion

HPOUTL

HPOUTR

GPIO

interrupt

logic

100k



DBVDD

Figure 30 Jack Insert Detection Circuit

The circuit requires a headphone socket with a switch that closes on insertion. It detects both

headphones and phone headsets. Any GPIO pin can be used, provided that it is configured as an

input.

HOOKSWITCH DETECTION

The circuit diagram below shows how to detect when the “hookswitch” of a phone headset is pressed

(pressing the hookswitch is equivalent to lifting the receiver in a stationary telephone).

GPIO

interrupt

logic

MIC

HOOK

SWITCH



HPOUTL

HPOUTR

MICL/MICR

AGND

680

2.2k

MICBIAS

PHONE HEADSET

WM9712L

Figure 31 Hookswitch Detection Circuit

The circuit uses a GPIO pin as a sense input. The impedance of the microphone and the resistor in

the MICBIAS path must be such that the potential at the GPIO pin is above 0.7

DBVDD when the

hookswitch is open, and below 0.3

DBVDD when it is closed.

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