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TLV320AIC3109-Q1: Switching between Single ended and Differential Microphone

Chirag Patel1
Prodigy 100 points
Part Number: TLV320AIC3109-Q1

Tool/software:

Hello

I'm looking into best and cost efficient way so our software can detect (e.g via ADC sampling) whether SE or DIFF microphone is connected. I was thinking about using a dual SPDT Analog Audio switch to allow  routing of Either MICP OR both MICP+MICN to the Codec.

Does TI has a reference design that describes this such configuration? I have attached a possible configuration. Can you please provide your feedback?

  • 0
    TI__Mastermind 46835 points

    Hi Chirag,

    The codec is capable of switching between SE and DIFF by a single register.

    My doubt is how you plan on determining that the microphone is SE or DIFF via the ADC data? I'm not sure that its possible.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 100 points

    Hi Jeff,

    The MICP_DIAG and MICN_DIAG signals (at the output of the switch) go to ADC inputs of uController. 

    When a single ended MIC is present between Analog switch's input ports S1A and S2A pins, the 680 ohm microphone impedance will work with voltage divider on D1 and D2 output pins of the switch. Similarly when a Differential MIC is present between Analog switch's input ports S1B and S2B, the diff. MIC's impedance will also form voltage divider with  D1 and D2 output pins of the switch. Based on detection thresholds, our software will determine if its a SE mic or DIFF mic. 

    Do you agree? I think if we can have a Teams' meeting it will help.

    Thanks

    Chirag

  • +1 in reply to Chirag Patel1
    TI__Mastermind 46835 points

    Hi Chirag,

    Thank you for the explanation. It seems reasonable. 

    Once your detection scheme has identified the type of mic, it can write to the codec to switch the input type accordingly. I do recommend that you power down the ADC before switching in order to prevent unnecessary pops.

    Best regards,
    Jeff McPherson