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to input differential adc

Ras Sharif50
Genius 3455 points

Other Parts Discussed in Thread: TMS320F28377D

Dear All,

I want to input some differential channels of tms320f28377d.

I have a question about using the bellow circuit.

( schematic from a TI note )

For n channel, should I to use n isolated supply voltage?

 

Regards,

Ras

  • 0
    TI__Guru 60865 points
    Hi Ras,

    You should be able to use a single 5V supply for all the op-amps. You may want to look at the supply noise for the 5V source and also the PSRR of the op-amps in question, but I think in general you shouldn't have too much of an issue.

    As far as the 2.5V reference, you should probably share the VREFHI voltage for a particular ADC with the signal conditioning circuitry on that ADCs channels. Since the VREFHI accuracy directly affects the ADC gain error, you may want to use a precision 2.5V reference IC instead of a voltage divider to generate this (unless your application doesn't care too much about gain error).
  • 0 in reply to Devin Cottier
    Genius 3455 points

    Dear Devin,

    Thank you for the comments.

    I read the other TI note containing the bellow circuit; "High-Voltage Signal Conditioning for Differential ADCs"