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TMS320F28P650DK: One question of ADC reference source.

Luke Chen
Expert 5090 points

Part Number: TMS320F28P650DK

Hi champs,

If customer wants to use external ADC reference voltage, we suggest customer using 3.0V(not 3.3V) for ADC reference to avoid the case the noise on the VDDA(3.3V) will imact ADC results.

My question is that is this also apply if customer uses internal 3.3V as ADC reference, the ADC results could be incorrect if Vin close to 3.3V?

Thanks and regards,

Luke

  • +1
    TI__Genius 11081 points

    Hello Luke,

    Yes, it is possible that the ADC accuracy is impacted if a case exists where can be Vin > 3.6V (VDDA+0.3V). The direct condition for VREFHI voltage does not apply in the internal reference case, because the VREFHI voltage is actually 1.65V and internal scaling is done.

    However, there is also a restriction on the input voltage range:

    The customer can use Vin up to 3.3V, but they need to be sure that some noise condition/other source of variation cannot push the input beyond the max range of 3.6V.

    Best regards,
    Ibukun