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ADS8866: Reference driver circuit for Vref=4V

Yash Mahajan
Prodigy 20 points
Part Number: ADS8866
Other Parts Discussed in Thread: REF3240

Above circuit is taken from page no. 25 of ADS8866's datasheet.

Please correct me if I'm wrong, But it seems to me that we can't connect REF3240's IN pin (Supply voltage) and ADS8866's AVDD to same voltage source.

REF3240 needs at least Vout+0.05 Input supply voltage. So it will need minimum 4.05V (Max 5.5V).

Where as ADS8866's AVDD can only take maximum of 4Volts.

Please tell me if there is something wrong in what I've wrote above!

Thanks!!

 

  • 0
    TI__Expert 3175 points

    Hi Yash,

    You are correct that the REF3240 (needs >4V) and ADS8866  (needs <= 3.6 V) supplies cannot be connected to the same voltage source. If you look at the schematic for the ADS8860EVM-PDK (this is faster version of the ADS8866), you'll see that we use an LDO (the TPS78833) to step the system supply down for the ADC.

    Regarding the REF3240, please note that the output of this device is 4.096 V so the input must be +50 mV from that  level (minimum ~4.15 V).