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ADS131E08: VREFP used for external circuit; maximum safe load?

Ken Henderson
Intellectual 670 points
Part Number: ADS131E08

Hello,

I would like to use the internal 2.4V reference in the ADS131E08 to create an external 1.44V ref for other circuits, and will use a divider.

The ADS131E08 uses an internal 25k+25k divider for feedback (R2 & R3, Fig 28), so I would like to know the maximum current I can safely use for an external divider. 

I was thinking 15k+10k for total resistance of 25k (2.4V*15/25=1.44V).

Thanks, Ken

  • 0
    TI__Guru 57336 points

    Hi Ken,

    Thank you for your post.

    The internal reference can be shared with other circuits, but I suggest limiting the current to only a couple hundred microamps. The divider circuit you proposed would draw about 96 uA, so the internal reference buffer should not have a problem with this. The best way to confirm would be to connect the VREFP pin to a source-meter and draw increasing current from the pin until you see the voltage droop.

    Keep in mind that any noise which couples onto your 1.44-V node may also couple back into the ADC reference (or vice versa). 

    Regards,