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ADS7871 External Reference

Is a 3.1V external reference voltage available for Vdd = 3.3V? In the datasheet in page 4, it says that the maximum input for the reference buffer is Vdd-0.2. Does this means that I can use an external reference of 3.1V either on:
-BUFIN with buffer enabled in case of high impedance source
-REFIN  in case of low impedance source

Thanks.

  • Hello Mohammed,

    When using an external reference, you may apply an external voltage in the range of 0.9V to VDD-0.2 to BUFIN; therefore you should be able to use an external reference of 3.1V when Vdd=3.3V. 

    The internal buffer amplifier can quickly recharge the bypass capacitor at the BOUT/REFIN pin between conversions. When using the internal buffer, a  bypass capacitor in close proximity to the BOUT/REFIN in the range beween 0.1uF to 10uF is required.  REFIN could be used as an input when the buffer is disabled when using a low impedance reference driver circuit.

    Thank you and Best Regards,

    Luis

     

  • Thanks a lot for the help and for the detailed reply.

    Regards,