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TMS320F28388D: Connecting both VDDA and VREFHI to 3.3V

Sheldon He
Expert 8585 points
Part Number: TMS320F28388D

Hi expert,

Though I find some discussion on this topic in this forum. I am wondering what will be the influence on ADC module (for it exceeds MAX value of VDDA - 300mv)

Thanks

Sheldon

  • 0
    TI__Guru 60865 points

    Hi Sheldon,

    VREFHI = VDDA is valid from a voltage levels perspective (the DS requirement is that VREFHI <= VDDA) and can be used if ADC performance isn't too important to the application.

    If VREFHI is connected to VDDA, then any noise on the supply will directly couple into the ADC results (there will effectively be 0dB of PSRR).  Connecting VREFHI to VDDA also presents other challenges since the design goals for a VREFHI driver (very low noise, high bandwidth, very high accuracy) are generally not needed for a typical supply driver.