INA226: 1uA measure current resolution for INA226

Hi Joseph,

have you forgotten the input bias current of INA226?

Kai

Hello Joseph,

Thanks for considering to use Texas Instruments. Your issue is likely related to input bias current as kai noted above as well as input offset voltage, both of which can cause considerable error for measurements on the lower end of the measurement range. Where was your amp meter located? Was it at the high-side or low-side? Have you tried shorting VIN+ and VIN- together? Ideally your current register would show zero. However, due to the input offset which is related to input bias, you will likely see a non-zero current or non-zero shunt voltage value. Also since the INA226 has an input bias current, the current pulled from the source on the high-side should be higher than the current passing through the low-side.

Thank you for reply.

What is the input bias current of INA226?

I think low-side measurement.

Currency is about 400mA through shunt  resistor(8.2ohm).

I = 3.3V / 8.2 = 0.4024

Calibration registor value is attached file.

I got it.
Input bias current of my INA226EVM is 3.07uA.

Does the input bias current vary each INA226?

When mass production process, how does input bias current measure?