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PCM2912A: Pleaes review: replacing the 3.5mm TRS Jack with an Electret Microphone

Mo Mizzi
Prodigy 220 points
Part Number: PCM2912A

Tool/software:

Just wanted to see if the following connection (green box) looks alright. We have used the PCM2912A with a 3.5mm Jack in the past. It worked great for us back then. 

However, we have a need to put an onboard Electret microphone instead. Can you please review the schematic below (specifically the green box) and see if anything stands out to you.

For testing purposes, I have connected the MicBias (MBIAS) and MicOutput (VIN) through a three way jumper. That I can feed into the +ve lead of the microphone.

  • +1
    TI__Expert 7050 points

    Hi,

    Yes, this looks fine for an electret microphone system. Make sure your MICBIAS is around 3V or higher for ideal operation of the microphone according to its datasheet.

    Let us know if you have any more questions!

    Best,
    Mir

  • 0 in reply to Mir Jeffres
    Prodigy 220 points

    Hi Mir,

    Thank you for quickly reviewing this and clarifying it for me.

    I'm not sure how to ensure MICBIAS is 3.3V or higher? Below is the audio portion of the PCM2912A. It is being powered by 5V.

  • 0 in reply to Mo Mizzi
    TI__Expert 7050 points

    Hi,

    MICBIAS is .75*VCCA for this device, so if your VCCA is 5V, then the mic bias will be 5*0.75 = 3.75V. That will work just fine for the mic.

    -Mir