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Use AD8232 AC Leads Off Detection feature to monitor interface impedance

Question asked by rbb on Jun 16, 2015
Latest reply on Jun 30, 2015 by rbb

Hi,

 

Connecting a potentiometer at the input leads of the AD8232 I was able to see the LOD+ signal toggling hi when the resistance was above 3 Mohm. Knowing the 0.7V comparator threshold from the datasheet, I have estimated the current that is internally generated at 100kHz to  be ~200nA in amplitude.

 

I would like to obtain the continuous impedance response at the interface not just the binary LOD signal.

 

Is there an easy way to externally demodulate the 100kHz signal that is internally generated for the AC leads off detection?

I have tried to use an instrumentation amplifier externally but I wasn't able to detect the 100kHz signal.

 

Please advice,

Thanks,

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