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INA240: INA240

Part Number: INA240

Hi All

I need to understand the error caused by putting external resistors in series with the inputs a bit more. If I am to apply gain error equation given in the datasheet, with 1000 Ohms external resistors, then the equation tells me that I would incur a gain error of 25% based on the calculated gain error factor of 75. Does this mean that my error as an example for the INA240A1 instead of the specified 20V/V +/- 0.2% maximum would be 20V/V +/- 25%? How is the "Gain Error Factor " derived and how does the "Input Bias Current vs Differential Input Voltage" plot fit in all of this?

Regards

ik

  • Hi imtiaz,

    External series resistance provide a source of additional measurement error, so we recommend to keep the value of these series
    resistors to 10 Ω or less to reduce loss of accuracy. If you chose bigger values your Gain Error can get pretty bad, as the one you are calculating of 25%. Section 9.1.1 from the datasheet explains the effect of external inputs resistors on the gain error.

    Also, if you want to learn more about how to calculate other errors in the system we have a video series that will be helpful for you. Specifically section 2 (sessions 5 –to 12) explain calculating error. training.ti.com/getting-started-current-sense-amplifiers