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2-Wire Setup and Measurement Range

Question asked by gimbal on Mar 29, 2017
Latest reply on Apr 19, 2017 by mark.ramos

I've read AN-1271 (Optimizing the ADuCM350 for Impedance Conversion) and from what I understand the following should be done:


  • Rcal - Set equal to the lowest expected impedance being measured
  • Rtia - Calculate to provide max voltage at minimum impedance
  • Ctia - Calculate based on Rtia


My questions are:

  1. What happens if the device sees a value lower than the expected minimum impedance
  2. In the 2-Wire example I don't see a call to set the Rtia anywhere, why is this not used?
  3. Is there any limit how high an impedance can be measured? For instance, with an Rcal of 1k ohm would I have trouble measuring impedances on the order of 10s of k ohms?