Single Microphone into two ADAU1977s

The ADAU1977 has a built-in Microphone input and Mic Bias circuit.  I have a redundant input
into my system to two ADAU1977s.  I have a single microphone that needs to
connect to one input on each ADAU1977.  How can I connect the single
microphone to the two ADAU1977s robustly so that if one of the ADAU1977 dies or
shorts the mic inputs the other ADAU1977 will still operate correctly with the
microphone?



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  • 0
    •  Analog Employees 
    on Mar 28, 2014 11:27 PM

    Hi Stephen,

    I am assuming you are using the microphone circuit as per the datasheet with the electret microphone which can support the recommended bias circuit. If that is the case then, connecting single microphone to two inputs can be wired to work with some redundancy.

    So if you plan to do it then connect the microphone bias resistors as usual but add 2k to 4kohm resistors in series to each of the inputs to ADAU1977 from microphone terminals. Please remember this is valid only for the microphone biased as shown in the application circuit of the datasheet.

    Thanks

    Rajeev

Reply
  • 0
    •  Analog Employees 
    on Mar 28, 2014 11:27 PM

    Hi Stephen,

    I am assuming you are using the microphone circuit as per the datasheet with the electret microphone which can support the recommended bias circuit. If that is the case then, connecting single microphone to two inputs can be wired to work with some redundancy.

    So if you plan to do it then connect the microphone bias resistors as usual but add 2k to 4kohm resistors in series to each of the inputs to ADAU1977 from microphone terminals. Please remember this is valid only for the microphone biased as shown in the application circuit of the datasheet.

    Thanks

    Rajeev

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