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INA214: Can I use the INA214 current sense op amp to measure currents as low as 2uA?

Grant Drennan
Prodigy 10 points
Part Number: INA214
Other Parts Discussed in Thread: INA190, INA186

Tool/software:

I am currently using the INA214AIRSWT in the bidirectional orientation, the op amp is being powered at 3.3V and the Vin range is between 1V and 3.3V. In our low current sense application "Rshunt" (the measurement resistor) is 47ohm. In this orientation can the INA214 measure currents in the range of 2uA-200uA or do I need a different current sense op amp?

I also noticed a ~20uA bias current when the common mode voltage gets to ~2.5V. This is messing up our current sense output, is there any way to get rid of this bias current to increase the accuracy of the INA214 in the 2.5V-3.3V range?

  • +1
    TI__Expert 5970 points

    Hello,

    Unfortunately the jump in bias current depends on the common-mode voltage, so the only way to reduce the input bias current is to keep the voltage low.

    Based on your design requirements, I would recommend using a different part with a lower bias current such as the INA190 or the INA186. These parts have bias current in the nanoamp range, so the bias current will not interfere with the measurement. The INA190 is the more accurate part, so it is probably most well suited to your design requirements as you are trying to achieve high precision.

    You could also consider using the 200V/V gain part in order to have better precision.

    Let me know if you have any more questions,

    Levi DeVries