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INA226 measure microampere

Martin Kessel
Prodigy 10 points
Other Parts Discussed in Thread: INA226, INA333

Hello Volks,

is it possible to measure microampere with the INA226?

We need to measure 0 - 5uA and 0 - 50uA.

 

 

best regards Martin

  • 0
    TI__Mastermind 25815 points

    Hello Martin,

    While the offset voltage of the INA226 is merely 10uV(max), the input bias current is large with respect to the desired current ranges.

    I therefore recommend that you look at our instrumentation amplifiers that have very low input bias current and initial input offset voltage (e.g. INA333).  You will then have to size the shunt resistor based on the initial input offset voltage of the device and the expected minimum load current.  A minimum load current of 0V cannot be accurately detected since it ideally does not create a voltage across the sense resistor.  Therefore a device will output at least the input-referred initial offset voltage times the gain.  You will also have to take into account the common-mode voltage.  The INA333, for example, has an input common-mode voltage range of (V-)+0.1V to (V+)-0.1V where the supply can be 1.8V to 5.5V.  Once an instrumentation amplifier has been selected you will need to select an ADC and/or microcontroller.  Once you get to that point please let us know and we can help you with the selection.