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AD7795/96 Internal Offset Cal

Question asked by AnalogPAT on Jul 21, 2015
Latest reply on Jul 30, 2015 by jcolao

I am using the AD7795 in a multichannel temperature application.  The product is calibrated at the factory with a system offset and gain cal before test. The calibration values are read from the AD7795 and stored in eeprom. They are loaded on power up. The current mode of operation is x16 gain, internal reference, chop enabled. I need to speed up conversions and turned off the chop and changed update rates to achieve this. I now see offsets.

 

My question is as follows:-

 

If I understand correctly, the internal offset cal removes errors in the ADC and the system cal removes errors external to the ADC.

If I add a periodic internal offset cal to remove the offsets caused by turning off the chop, won't I lose the system calibration zero offset ? Is there some way of combining the two ?

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