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PCM3168A: Signal processing before ADC input / after DAC output

Robin Maeder
Intellectual 450 points
Part Number: PCM3168A
Other Parts Discussed in Thread: OPA1664, OPA1662

Hello All

In my current project I am thinking about using the PCM3168A audio codec. Every audio input needs to be passed to any of the outputs. 

My circuit needs to support these audio inputs:

  • 3 x Single-ended analog MEMS microphone
  • 3 x Differential line input

And it must provide these audio outputs:

  • 3 x Speaker/headphone output
  • 4 x Differential line output

For the speaker/headphone outputs I would use an additional speaker amplifier, for the MIC inputs a MIC preamplifier and for the line outputs a line driver. 

What needs to be done with the line in signals before going onto the ADC inputs? 

Is the PCM3168A the right device for this use case or would you recommend another codec?

What about the needed amplifiers and drivers. Any recommendations for the number of channels I need?

Thanks for your help

  • +1
    TI__Mastermind 23050 points

    Hi Robin,

    Yes I think the PCM3168A is the best device for this given the number of channels you need to support. Other options would require multiple codecs. The PCM3168A does not integrate the front end amplifier though so you will want to do all of your intended signal conditioning (filtering, gain, etc.) externally. You should set the gain/attenuation to utilize the full dynamic range of PCM3168A. Attached is an example schematic from our latest evaluation board that you can use for reference. We use the OPA1662 and OPA1664 on this board which are dual and quad channel op amps in the same family. I hope this helps!DC144A(001)_Sch.PDF

    Best,

    Zak

  • 0 in reply to Zak Kaye
    Intellectual 450 points

    Hello Zak

    Thanks for your fast reply which helped a lot. Maybe it would be easier/cheaper to use a more complex codec like WM8281ECS/R to reduce all the external circuits.

    Best regards