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INA240: Input Impedance

Part Number: INA240

Hi.

 there is not information about the input impedance of INA240 in the datasheet.

Can you provide information about it?

  • Hi Shlomi,

    the common mode input resistance is not constant but depnds on the common mode input voltage according to figures 7-14 and 7-15 of datasheet. The input resistance can be estimated by calculating the gardient of these curves:

    R = dU_common_mode / dI_input_bias

    which is about

    R = (70 - 10)V / (200 - 80)µA = 500k

    for common mode input voltages >10V.

    Kai

  • Hello Shlomi,

    As Kai mentioned, the common-mode input resistance at each input pin is variable depending upon what the VCM is and can be easily deduced using Figure 7-14 and 7-15.

    There is also a typical 6kΩ (+/-20%) differential input resistance in between IN+ and IN- pins.

    Sincerely,

    Peter