ADE7758: Offset at high gains

Document created by analog-archivist Employee on Feb 23, 2016
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We have a problem with ADE7758 in current gain and offset. We have observed
that current offset is increasing with any sign of current gain at low current
values.
For example, at 30A full range current inputs for zero current we have for gain
zero about 0.031A offset. With gain plus or minus 100 we measured 0.061A. For
+/- 1000 we measured 0.145A. For higher currents chip is slowly going to work
as expected i.e. offset is sensitive to sign of the gain. This behavior is chip
dependent.

 

There is a problem when using the xIGAIN register. 
An increase in the xIGAIN register causes some high frequency noise to
introduced into the IRMS measurement.  
This HF noise only causes an error in the IRMS measurement and does not effect
the other measurements.

We recommend that the customer should leave the IGAIN register set at 0 and
perform a gain adjustment on the readings he gets from the IRMS register in his
MCU.

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