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INA240: how to cancel output noise?

Yuan Tan63
Expert 3280 points

Part Number: INA240

Hi,

customer use INA240A1 for 3-phase current sensing in 48V motor drive system. phase current is 14A. In startup, output suddenly showed a ±50mV noise. customer stopped the PWM for motor and short the INA240's input, here is still a ±50mV noise. It disappeared only after repower.  Why it didn't disappear even no input? do you have any suggestions for this?when change phase current to 7A, the noise never show up. why it influenced by sampled current? thank you.

here is sch and waveforms:

(the purple line is output of INA240, you can see it suddenly show the noise from the arrow)

( ±50mV ripple)

thank you!

Best regards,

Yuan

  • 0
    TI__Mastermind 36740 points

    Hi Yuan,

    Does this problem occur only for a small percentage of samples? It bears some resemblance to a silicon issue identified a while back that has since been fixed. Please refer to the first reply within this post for a description of the issue.

    To verify, you could request customer capture +3.3D supply and see how fast it rises. At the same time you could have customer replace with INA240-q1. The issue should go away if it is indeed caused by the same mechanism.

    Regards, Guang