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EVAL - AD5292 - connection and polarity

Question asked by Roman.Sh on Jun 13, 2016
Latest reply on Jun 15, 2016 by Roman.Sh

Hello,

I'm using Evaluation board for AD5292 in Automated Test bench to change output voltage of the DCDC Converter. I added a connector (J8 below) in parallel to Converter feedback resistor and plug it during the testing. However I found that for some reason the polarity of the connection of the Digital Potentiometer is important. I measured the resistance and voltage on the Evaluation board and as expected it looks completely floating Rb, Ra and Rw are disconnected from Analog Ground and the voltage on these pins is 0.

Circuit A: Working with certain polarity.

Circuit B: Doesn't work with any polarity

 

From my observation I can conclude that for some reason the Dig. Pot is grounded (also I don't see it in stand alone resistance measurement).

 

Please advise if you have any ideas for the reason of this phenomena (I have 2 Evaluation boards and both show the same results)

 

Thank you in advance,

Roman

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