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Hello, I'm using an aic3206 in an embedded Linux system. When I enable headset detection, the MICBIAS pin is driven with a low-duty-cycle waveform of approximately 15 microseconds high, 500 microseconds low.
From this other e2e question, I gather that the headset detection in the aic3206 works similarly to the aic3101 family. In the linked app note, Figure 16. Pulse Scheme shows a waveform similar to what I've measured above.
This is causing a continuous audible squeal at just under 2kHz in my headphones for as long as I have headset detection enabled. It's worse in some headphones than others, but it's at least faintly audible in all of the headphones I've tried. Is there a way to improve this behavior?
That's the scheme for headset detection with external micbias, can you use device micbias?
I should clarify, I'm not using an external voltage reference to bias the microphone; I'm using the codec's MICBIAS pin to bias the microphones. Here's the relevant part of my schematic:
(yes, I've noticed that the INTMIC_N/INTMIC_P have their DC-blocking capacitors in the wrong place. I'm currently concerned about the MICBIAS/ MICDET/IN3_L/SLEEVE part of the circuit.)
Your headset is cap-less and based on figure 11 of the apps.note, you can use the other path to bypass the det_pulse scheme as shown below.
Regards.