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ADS8361: Driver BW, max Rsource and external reference

Thiago Moraes
Prodigy 30 points
Part Number: ADS8361

Hi,

I am considering an external reference for the ADS8361.

I found no mention of an internal C_ref on the ADS8361 datasheet.

Other ADCs have it. For instance, from sbas523d (ADSxxx3  Simultaneous Sampling ADC on sbas523d, page 46: If the reference voltage is external, the operational amplifier must be able to drive the 22-μF capacitor without oscillation. 

But on the ADS8361 datasheet, it informs that the ADS8361 external REF pin is buffered, page 10: If an external reference is used, the second buffer provides isolation between the external reference and the Capacitve Digital-to-Analog Converter (CDAC). This buffer is also used to recharge  all of the capacitors of both CDACs during conversion.

So I'd like to confirm that I can use any external reference, without any series resistor or external capacitor, and it will not oscillate. 
  • +1
    TI__Guru**** 180961 points

    Hi Thiago,

    Welcome to our e2e forum!  You are correct, you do not need an additional amplifier ahead of the REFIN pin on the ADS8361.  Having place holders for a low pass RC filter (if needed in the end) would be a good idea if you have the board space available.