when I read IRMS with no load I get positive offset around 0x531, so IRMS never goes to zero or near zero when no load, tried CH1OS and IRMSOS with mixed results , never was able to clear that offset.
any ideas ?
There might be an offset at no load but it can be corrected using the registers that you have mentioned. Firstly, when you say NOLOAD, what do you mean exactly? Do you not have any input connected or do you have a very small input? How much is the input noise? Did you try reading IRMS multiple times to see the repeatability in measurement? Next, have you tried to offset calibrate the setup by following the procedure described on page 45 of the datasheet?
the offset is contestant, and I read it multiple times, it is always within the 0x531 range, managed to lower it down by turning the digital integrator on, even that I am using shunt resistor
that offset is in when there is no load connected, any load connected even if small I see change in the reading in the right direction, but never was able to remove the offset using the 2 registers,
when I try to calibrate using the datasheet method, any change to CH1OS or IRMSOS give me mixed results,
like going negative when no load, even changing CH1OS with very small value
when I short CH1 inputs externally or internally using the registers I get the same results
I believe you might have the HPF disabled. Can you try enabling it? Also, do you see it on both channels? Can you provide sample register readings before and after calibration so that I can get a sense of what order of offset are we talking about?
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