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AD7793: REFIN pin draws 168 uA - is it broken?

Question asked by AndreasKl on Dec 24, 2014
Latest reply on Jan 19, 2015 by jtee

I have an AD7793 with a PT1000 RTD. I use a 210 uA excitation current to excite the RTD. The same current then goes through a 2.7 kO hm reference resistor to ground. However, it appears that the majority of the current does not go through the reference resistor but to the REFIN+ pin: I measure 168 uA being drawn to the REFIN pin and only 43 uA going through the reference resistor.

 

Is my AD7793 likely broken or do I possibly have something wrong about my configuration/circuit? The AD7793 seems to function normally otherwise. I can read and write all registers, obtain conversion values, the proper reset values etc.

 

Thank you very much!

Andreas

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