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TPS54218: Rush current on the output

Dice-K
Mastermind 6730 points
Part Number: TPS54218

Hi support team,

The rush current on the output side at startup is approximately 1.28A.
Is there any problem with the device?
No current flowing backwards was observed at the input of TPS54218.
I think it passes through the inside of TPS54218 and flows to the GND side.
Does this kind of phenomenon occur?

Yellow: Output current
Green: Input 5V
Purple: Output 3.3V

Regards,
Dice-K

  • +1
    TI__Genius 16200 points

    Hi Dice,

    I think the negative current happens because the VOUT is already biased >0 before startup. Once soft-start is initiated, the SS cap voltage is ramped up from 0V and VOUT would have to follow this. The negative current is to pull VOUT to zero and then follow the SS cap ramp up.

    You could try completely discharging the VOUT before ramping VIN up and check. There should be no negative currents in this case.

    Best regards,

    Varun