Hi Kenneth43,
I use my load cell between 3kg to 3.8kg basically. I did not get the following
"Then the poor gain TC of the AD620A, 50ppm/°C will add a lot more drift. 16mV*50ppm/C is 0.8 µV/C, added to the 0.3µV/°C on the first row."
But there is some questions about your statement. How can you explain some circuits have nearly zero drift and some has much more.
In my application I have nearly 15 circuits working at the same time. you power on the system wait about 10-15 minutes in order to build temperature of IC's. And zero all circuits. Then start to wait and see the drift. You will see some circuits output becomes +1gr some is 0.5gr some is -0.5gr some is -2gr. so their drift is not similar.
How about effect of power supply voltage. I have 10V reference IC suppose its output changes 10ppm/C or my negative regulator has 50ppm/C.
Will drift of a circuit always be the same. Suppose;
temperature is 20 degrees. you power up system,make zero the output and wait 3 hours. output becomes 1gr. one day later again you make same measurement at same temperature. will output be same?