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TLV320ADC3101: input range issue

wxyxiangyang
Intellectual 670 points
Part Number: TLV320ADC3101

Dear expert

I am using the ADC3101 for the vibration related application, the sensor output to the ADC is +-2V, but as I know, the ADC can support only +-1 V, so 

our hardware engineer use a -6dB chip gain for attenuation, but as I know, the ADC has a register for gain, do you suggest we use the analogue or digital gain register to replace the hardware -6dB gain. which one has higher accuracy?

  • 0
    TI__Guru 62085 points

    Hello,

    The analog gain (PGA) is in series with the front-end attenuation network and before the ADC inputs.  Since the max single-ended analog input voltage to the ADC is 0.707Vrms, an input of this level will return a full-scale output.  With a +/-2V input you'll need -6dB of attenuation to prevent an analog saturation of the ADC inputs, and the resulting ~+/-1V input to the ADC will result in a full-scale input.  Adding digital gain afterwards would result in a saturated (clipped) output result.