AD8226 offset voltage

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Hi

I've selected AD8226 in my design for self diagnosis of 0-20mA current loop.

I simulated AD8226 for sensing a constant current 1mA across 40E resistor. Below is the result for same.

Below are the parameters set. +Vs=30V , -Vs=-6V G=1 Sense resistor=40E current flowing=1mA Observing output voltage of 40.78933mV(Fig 1 and 2) but Vout=I*R = 1mA*40 = 40mV

Again I simulated AD8226 for sensing a constant current 20mA across 40E resistor. Below is the result for same.

Below are the parameters set. +Vs=30V , -Vs=-6V G=1 Sense resistor=40E current flowing=20mA Observing output voltage of 800.7578mV(Fig. 3 and 4) but Vout=I*R = 20mA*40 = 800mV

It is observed that nearly 0.7mV is additionally added to output, which is 700uV, But in the datasheet it is mentioned that 50uV is the input offset voltage. As gain is 1 output offset also should be 50uV.

Please let me know if I'm missing out anything.

Thanks and Regards

Nidhi P Shetty