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INA283: INA283 Gain

Part Number: INA283

Dear Guys,

Regarding datasheet, the gain should be 200 +/- 1.4%. I want to learn how to verify the gain. Did you have any suggestions on that? Thanks.Ian.

  • Hey Ian,

    You can quickly verify the general gain of the part by applying a small voltage signal at the input pins (5mV) and measure the voltage from OUT to GND to make sure that the voltage is 200V/V * 5mV = 1V. This assumes you are connecting REF1 and REF2 to GND.

    If you actually want to verify the 1.4% gain error, the you will want to emulate the test condition for this gain error spec (see below). Meaning you would apply whatever range of input voltages needed to get the OUT to swing from GND+0.5V to (V+)-0.5V. You would record the measuremens of Vin versus Vout-to-Vref and ensure slope (or gain error) is less than 1.4%.

    Best,

    Peter Iliya

    Current Sensing Applications

  • Dear Peter,
    Can we use input=1.2mV to measure it? We using 1.2nV to measure looks not good result. Will over 1.4% result. Thanks.
  • Hey Ian,

    Are you injecting 1.2mV or 1.2nV? Technically we do not specify INA283 (gain 200) to have 1.4% gain error with a 1.2mV input differential voltage since the output would only go to 240mV. The output needs to go to 500mV, so input = 2.5mV. Injecting a 1.2nV signal will definitively not work.

    In addition to all of this I believe you might be mistaking gain error and total error for a single measurement. Gain error is determined by sweeping (changing) the output voltage of part from point Y1 (GND+0.5V) to point Y2 (V+-0.5V). This is done by injecting input voltages X1 to X2. The slope of this line is "m" and thus gain error =100*|m-200|/200.

    In this calculation, offset (Vos) is removed. If you are injecting a 1.2mV signal you will see worst case 5.8% error just from the maximum possible input offset voltage (Vos = +-70uV). This is considered the offset error and is contributing to total error you see. Max Vos error = Vos_max/Vshunt*100 = 70uV/1.2mV = 5.83%.

    Best,
    Peter Iliya
    Current Sensing Applications