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digiPot common GNDs (AD5292/91)

Question asked by a.c on Apr 21, 2016
Latest reply on Apr 25, 2016 by msamera

Greetings

 

I have a rather general question regarding the AD5292/5291: Is it okay/should I connect Vss and B?

I am asking, because I am currently using four of them in a daisy chain configuration. It seems though one of them is kind of damaged (by now). So far I had them connected (together with GNDlogic). If I do so, three work perfectly fine, but the fourth just takes about the set percentage regarding the voltage inbetween Vdd and Vss, not regarding the voltage that is applied to A and B. It thus also happens that the voltage between B and W exceeds the one between A and B, also B-W does not change when changing A-B (unlike the other three).

If I do not connect them, all four of them work, but the "damaged" one has a significantly lower value (B-W voltage) than the remaining ones, furthermore the accuracy seems lower (ie 75% results in 80-85%).

I suppose I should indeed connect all GNDs here, I am just not sure what caused the (possible) damage, and would like to know if it could be this, to ensure it does not happen again. Power-up sequence is applied, programming via SPI still works(RDY low).

 

Thank you in advance.

 

a.c

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