STW5095 Datasheet, PDF (19/69 Pages) STMicroelectronics – Low Power Asynchronous Stereo Audio Codec with Integrated Power Amplifiers

STw5095
3 Functional Description
3.16 Headset plug-in and push-button detection
STw5095 can detect the plug-in of a microphone connector and the press/release event of a
call/answer push-button. An application example can be found below, while specifications can
be found in Section 9.4 on page 54.
Figure 3. Plug-in and push-button detection application note
VCCA
3kΩ
1.5kΩ
Call/Answer Button
10µF
HDET
200nF
AUX1L
200nF
AUX1R
STw5095
CAPMIC
From Driver
Generic Connector
3.17 Microphone biasing circuit
The Microphone Biasing Circuit can drive mono or stereo microphones and can switch them off
when not needed in order to save the current used by the microphone biasing network. Two bits
control the behavior of the microphone bias circuit: MBIAS in CR17 enables the circuit (fixed
voltage at MBIAS pin), while bit MBIASPD in CR17 affects the behavior of MBIAS pin when the
function is not enabled. In particular when MBIASPD=1 the MBIAS pin is pulled down,
otherwise it is left in tristate mode. The specification for the microphone biasing circuit can be
found in Section 9.6 on page 55, and an application note is shown in Section 17 on page 66.
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