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TLV320AIC3254: DC-coupling on single-ended input mode

Evan Cornell
Expert 1410 points
Part Number: TLV320AIC3254

TLV320AIC3254 is powered with 1.8V. 

I have analog signal conditioning that results in a single-ended analog signal with common mode dc bias of 0.9V. 

Is there any issue with omitting the AC-coupling caps on TLV320AIC3254 IN1_L / IN1_R pins in this use-case? 

Would any difference in voltage between my analog signal conditioning's 0.9V bias point and the TLV320AIC3254 bias point be gained up by the PGA, potentially saturating output, depending on gain level of PGA?

Is it possible to output TLV320AIC3254 common mode voltage to one of the analog pins? 

  • +1
    TI__Mastermind 42455 points

    Hi Evan,

    The AC coupling caps are required so that the internal bias generated for the ADC doesn't conflict with the source's common mode voltage, even if they are nominally the same. Otherwise you risk losing range on the ADC. 

    You'll see the common mode voltage on the input pins prior to the caps when the ADC channel is enabled. However you can't set the voltage to be on an output pin or anything like that.

    Best regards,
    Jeff McPherson