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TS3A227E microphone signal

Andrew Wood
Prodigy 10 points
Other Parts Discussed in Thread: TS3A227E

We are considering the TS3A227E for a 4 pole headset jack. We need the keypress detection function, but my question is: does the TS3A227E remove the DC level shift which key presses will impose on the microphone audio?  I suspect that the DC shift will produce a 'pop' on the audio, which is likely to be very loud considering the small amplitude of the microphone signal.

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    TI__Genius 9860 points
    Hi Andrew, thanks for the message. The appropriate engineer has been notified and will reply shortly.
  • 0 in reply to C. Ryan Land
    TI__Expert 6395 points

    Hello Andrew,

    The TS3A227E does not manipulate the microphone voltage in any way.  If a key is pressed there can be an audible pop sound if not filtered internally by the codec.  However the change in microphone voltage contains the information about what key is pressed so we would not want to remove it.

    We also experimented with separating the MICBIAS from the headset and providing internal references but this actually caused more noise.

    Hope this helps,

    Andrew