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TPS54428: Over Current Limit

user5837177
Prodigy 40 points
Part Number: TPS54428

Hi all,

Im using TPS54428 in my device under mass production as a buck converter that converts 12 V to 5 V. However, when I made a mistake such as short circuit due mechanical touching or other reasons, my 5 V rail becomes short circuited to ground. Then, I check this with my multimeter buzzer (without power on my circuit), 5 V to Gnd is connected permanently. In order to fix my circuit, I replace TPS54428 with a new one, and it works. As a result, TPS54428 does not limit its current as mentioned in datasheet and burns (This was occured in 5 devices up to now). I need your ideas or comments about this problem because there is an ongoing mass production process and I need to solve this problem. Does TPS54428 really have over current limit?

Thanks.

Best Regards

  • 0
    TI__Mastermind 27470 points
    Hi :
    TPS54428 have the OCP function. the OCP typical value is 5.3A low side. so the average current is 5.3A+0.5*Iac. Iac is determined by you inductance and output voltage.
    below is some suspect:
    1. whether you have input spike voltage when output short.
    2. whether you inductor will come to saturation when circuit OCP ,because it need high OCP to protect inductor saturation.

    it is better to have SW voltage waveform and inductor current waveform. we can see what happened when 5V short to ground.

    Thanks

    Daniel