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Problem with TPS564208

Giuseppe Scarpi
Prodigy 110 points
Other Parts Discussed in Thread: TPS564208

Hello, I am writing to the forum hoping to get an answer to a worrying behaviour of TPS564208.

One of our customer is experiencing problems with this IC: when the board is turned on, the TPS sometimes gets destroyed. An analysis on the board reveals that the SW pin is grounded, so I suspect the internal N-MOS melted.

This is something I cannot explain. The load connected to the board is a Raspberry 3, with a maximum expected current of 2.5A, while this specific TPS is designed for 4A and a much higher peak current.

I used a Webench design, only replacing the suggested inductor value from 3.3uH to 4.7uH.

To add a useful information, it seems that the problem happens during reset, that is when the TPS is turned off via ENABLE pin and then turned on.

Could you please give some suggestions? The situation is critical as we are starting the production.

Thanks

Giuseppe

  • 0
    Prodigy 110 points
    Today I executed a series of quite harsh tests, and the component behaved very well:
    - output in short-circuit
    - pure inductive load
    - resistive, resistive/capacitive, resistive/inductive loads and output current higher than absolute maximum rating.

    In all cases the TPS survived the test, and the internal overcurrent circuitry effectively saved the IC.

    I was able to destroy the TPS only applying an external voltage higher than the programmed output voltage. In this case, VIN and/or SW gets shorted to ground. If the voltage is high enough, you may also enjoy a nice white smoke....

    I understand this test can seems idiotic, yet in my specific case there are chances that this situation may happen.
    Of course the TPS is not designed to work as a sink load, so the only reasonable solution is to protect the output with a diode.

    Any comments?