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INA180: INA180:rush current

Kenta Yamada
Prodigy 190 points
Part Number: INA180

Dear sir, 

We would like to confirm if exceed 8mA or not.

We will connect the capacitor to the INA output.

For specification of Absolute Maximum Ratings, Maximum current output is 8mA

But for figure 19, typical characteristics is over 8mA.

INA180_rush_current.xlsx

Thanks & best regards,

  • 0
    Prodigy 190 points

    Dear Sir, 

    Sorry but replace attached file for before folum.

    4657.INA180_rush_current.xlsx

    Thanks,

  • 0 in reply to Kenta Yamada
    TI__Mastermind 31840 points

    Hi,

    At least under DC condition, the device shouldn’t be able to source 48mA (sinking yes). However it is possible that for a brief moment in-rush current that large can get through. Can you please zoom in on the pulse and see what it looks like?

    The other possibility is that measurement artifact makes the pulse look bigger than it actually is.

    The part is capable of delivering more than 8mA DC. However this spec is to protect the metal trace’s long term reliability under sustained large (>8mA) current. For short pulses, this restriction can be relaxed.

    When not sure, a current limiting resistor should help reduce the current.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 190 points

    Dear Guang,

    Thank you for your reply.

    Well, noted.

    Blue line wave is output current.

    Peak current is 58mA. 

    But pulse width is very narrow(16us or less).

    Would you please confirm to effect device damages.

    Thanks & best regards,

    K. Yamada

  • 0 in reply to Kenta Yamada
    Guru 140200 points

    Hi Kenta,

    keep in mind that the uncharged 1µF cap at the output of INA180 looks like a short-circuit and you force the INA180 to charge-up the 1µF cap with the short-circuit current. You can also see that the internal short-circuit protection sets in. You heavily overstress the INA180 by this Scream. Such a situation should be the absolute exception which may occur one time a week or so, but not perdiodically during standard operation.

    As Guang already mentioned you should add a current limting resistor:

    This will also prevent instability caused by the huge capacitive load.

    Kai

  • +1 in reply to kai klaas69
    TI__Mastermind 31840 points

    Hi Kenta,

    Thank you for the additional scope plots. These pulses are short. Also they are grouped far from each other based on previous figures (low duty cycle). The situation is not we would consider as risky, it should be OK to use as is, or you could include a small limiting resistor.

    Thank you Kai for the great simulation demonstration.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 190 points

    Dear Guang,

    thank you for your cooperation.

    Well noted, thanks!

    I will consider to add small limiting resistor.

    Best regards,

    K. Yamada

  • 0 in reply to kai klaas69
    Prodigy 190 points

    Dear Kai, 

    Good day.

    Thank you for your advice.

    Well, noted.

    I will consider to add small limiting resistor.

    Thanks & best regards,

    K. Yamada