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INA241A: Current sense amplifer offset

Thomas Kofoed-Hansen
Prodigy 180 points
Part Number: INA241A

Is the offset specification multiplied by the gain when calculating the total root squared error?

I would expect to have to multiply the offset by the gain but looking at the examples it seems I should not.

  • 0
    TI__Mastermind 29750 points

    Hello Thomas,

    For VOS would be an input error specification.  You can see more detail here: https://www.ti.com/video/series/ti-precision-labs-current-sense-amplifiers.html

    Basically the error from VOS will be on the input.  An example is done with global conditions on the VOS error not adding PSRR, CMRR, Drift or other factors.  So for an Rshunt of 1mΩ and a current of 1A we would get a Vin of 1mV and an output of 10mV for the A1 version.  The error seen by VOS at the input is 20µV max at the input or 200µV at the input.  The below numbers are all using Max error for VOS for the same senario

      

    Device Gain V/V Vos Spec (µV)  Max Current Error Voltage Error seen at output
    INA241A1

    10

    		 20 20µV/1mΩ =  20mA 20µV*10V/V = 200µV
    INA241A2 20 15 15µV/1mΩ =  15mA 15µV*20V/V = 300µV
    INA241A3 50 10 10µV/1mΩ =  10mA 10µV*50V/V = 500µV
    INA241A4 100 10 10µV/1mΩ =  10mA 10µV*100V/V = 1000µV
    INA241A5 200 8 8µV/1mΩ =  8mA 8µV*200V/V = 1600µV