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TLV320ADC3100: Mono input Circuit design check

Teresa Chiu
Prodigy 690 points

Part Number: TLV320ADC3100

Hi expert,

Could you help to check below circuit (Fig.1) connection is correct or not?

Fig.2 is the function block for you reference. The audio amp is a mono output with differential mode.

Fig.1 SCH

Fig.2 Function block

  • 0
    TI__Mastermind 30240 points

    Teresa, 

    an unused micbias can be left floating,  any unused input pins should be terminated with a 0.47uf capacitor to GND.  

    What kind of Audio levels are coming from the Audio Amplifier?  I don't really see any attenuation circuit in the schematic you provided.  I would assume that there is something like this  somewhere?  the full-scale input of the ADC3100 is 1.414Vrms differential,  and the abs max is -0.3 -> AVDD+0.3V

    I assume that the I2C pull-ups are elsewhere on the schematic. 

    Best regards,

    -Steve Wilson

  • 0 in reply to Steve-Wilson
    TI__Prodigy 690 points

    Hi Steve,

    Could you help to correct the connection if it is wrong for mono input signal?

    About "unused input pins should be terminated with a 0.47uf capacitor to GND", NC pin should be followed? 

  • 0 in reply to Teresa Chiu
    TI__Mastermind 30240 points

    Teresa, 

    I don't see anything that I would consider "wrong" for a mono signal.  it looks like they are connecting a differential output to a differential input,  and that seems normal. I also suspect that they are using two channels so they could average the two channels and achieve +3dB SNR or for redundancy.  The inputs they are using are the correct pins for each channel.

    Because of the redundancy, and the 0 ohm resistors connecting the two channels I wasn't sure if there would ever be a case where the inputs were not used.  IF there is a use case where 10R102 and 10R103 were not installed for example.  it would be best of those inputs could be terminated. 

    best regards,

    -Steve Wilson

  • 0 in reply to Steve-Wilson
    TI__Prodigy 690 points

    Hi Steve,

    Thanks for your suggestion.