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INA200, output current of CMPIN pin

Shinichi Inoue
Guru 21781 points
Other Parts Discussed in Thread: INA200

Dear Specialists,

My customer is evaluating INA200, he encountered unexpected output delay time.

He wants to see the reason why.

Could you please see attached file for more information and advise?

 I appreciate your great help.

Best regards,

Shinichi

question about INA200.pdf

  • 0
    TI__Genius 14825 points

    Shinichi,

    We are currently reviewing this question and the design materials.  We think there is a 10kOhm input impedance that may be causing this behavior and we want to try it on a bench setup.  We will be able to try this on December 5th US time and provide a more solid answer then.

  • 0 in reply to Jason Bridgmon
    TI__Genius 14825 points

    Shinichi,

    We tested the customer's circuit on 3 different boards and none of them produce the same behavior as the customer sees.  With CMPIN connected or disconnected, the rise time is always ~17mS.  We tried two different ways of driving R1: one with the OUT of the part, the other with a direct voltage source.

    We looked into the possibility of an input impedance that could be causing issues but we were unable to find one.  It would need to be about 50k to make the math work out for a time constant of ~12mS and we couldn't find that in the design or otherwise.

    Has the customer tried debugging this with different capacitors and resistors to eliminate any potential bad parts?  Is there any other part to this schematic that may be relevant to why this rise time is changing?

  • 0 in reply to Jason Bridgmon
    Guru 21781 points

    Dear Jason

    Thank you for your reply and confirmation.

    I am going to send the answer to the customer and make him test which part is the problem.

    And I'll feedback to you if I receive the result.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi