[volt-nuts] Fluke 887 mod with LTC1050
csteinmetz at yandex.com
Thu Apr 27 15:18:20 EDT 2017
> but I recently noticed the meter reads -0.08 when the
> input is open on the 1V range and the null switch is on 0.0001
> This equates to a -8uV reading.
> I believe this is due to the input bias current of the LTC1050
> * * *
> However, this would imply an 8pA bias current,
> which is much higher than expected.
I am attaching the relevant portion of the LTC1050 datasheet. Note that
at 25C, the 1050 has an input offset current spec of +/- 20pA (both
typical -- max is ~5x worse). I would expect a total input offset of
+/- 20uV (typical) in your circuit. (The 0.5uV typical input offset
voltage is not a significant contributor in this context.)
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