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TMS320F28388D: Fc bandwidth (bandwidth pushed by OPA) on ADC VREFHIx

Eric Chen
Intellectual 1350 points
Part Number: TMS320F28388D

Tool/software:

Dear expert, 

The fc bandwidth (bandwidth pushed by OPA) on ADC VREFHIx,

according to the document design to 1MHz,

how much is generally recommended?

Best Regards,

Eric Chen

  • +1
    TI__Mastermind 32755 points

    Hi Eric,

    VREFHI is a fixed DC source, however during conversion, the ADC SAR block will actively switch the capacitor array to charge/discharge to determine the magnitude of the signal stored in the sampling capacitor through internal comparators and voltage divider strings. For this reason, the VREFHI line will see switching noise.  The opamp driver should have the bandwidth to respond to the fast transient current requirements caused by internal ADC SAR capacitor array switching/charging.  This would be at least equal to the ADC sampling rate.

    Regards,

    Joseph 

  • 0 in reply to Joseph Casuga
    TI__Intellectual 1350 points

    Dear Joseph,

    Thanks for your help!

    Best Regards,

    Eric Chen