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INA214-Q1: What does gain error mean?

Elec Cheng
Expert 7055 points
Part Number: INA214-Q1

Hi Expert,

As said in datasheet, INA214-Q1 has fixed gain. But they choose large Rs, such as 10Kohm. So the calculated gain error would be very large, near to 90%. Then they use Gain_real= 100*(1-90%)= 10 as the real gain simply because they need a smaller gain. I know it's against what datasheet says and inappropriate but I cannot tell a solid reason. Could you please help explain what gain error means and why this method is not applicable? Thanks!

BR,

Elec Cheng

  • 0
    TI__Mastermind 30350 points

    Hi Elec,

    To understand their meaning, you may view this short training video on gain and gain error of current sense amplifiers.

    There are a few reasons why it is not recommended to modify gain with Rs. First Rs normally doesn’t track device’s internal resistors, which can lead to drift. Second, all internal resistor values are typical. Lot variation can cause deviation in real gain. Third, the equation works when Rs is small compared with Rint; if Rs is comparable to Rint, the equation may deviate quite a bit from actual value.

    This gain reduction method can be used as long as these limitations are taken into consideration.   

    Regards, Guang