wm9712l Wolfson Microelectronics plc, wm9712l Datasheet - Page 75

• Manufacturer Part Number: wm9712l
• Description: Ac?97 Audio And Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
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JACK INSERT DETECTION
HOOKSWITCH 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.
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.
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).
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.
interrupt
interrupt
logic
WM9712L
logic
HPOUTR
HPOUTL
GPIO
HPOUTR
HPOUTL
AGND
MICL/MICR
GPIO
MICBIAS
100kΩ
DBVDD
680Ω − 2.2kΩ
-
-
-
-
switch closes
on insertion
PHONE HEADSET
MIC
L
47Ω
R
PD Rev 4.5 August 2006
HOOK
SWITCH
WM9712L
L
R
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