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TPS54360 Failing short when powered by 36 volts

Other Parts Discussed in Thread: TPS54040, TPS54360

Hello, we recently switched form the TPS54040 because we have switched out power brick from 30V to 36V and want the headroom to go to 48V if necessary.

I have 6 boards fail shorted with the TPS54360 at 36 volts which takes out everything down stream. Schematic attached.  

 5504.power_test.PDF.

They seem to be fine at 30V but not at 36V. The enable is open which I thought would be ok based on the datasheet.

Desperate for a solution.

Thanks,

  • Did you just replace TPS54040 with TPS54360?  It may require re-compensation.  I also see you only have 10uF output capacitance.  If you have an inductor on the input, you may need some bulk capacitance as well as the ceramic.  Do you hot plug the input supply?  that can cause transients above the abs max.  Has anyone reviewed your layout?  let me know the history of your design.

  • No we did not just swap parts, the TPS54360 was designed in.

    We do hot plug the supply but have checked for overshoot and it powers up smooth.

    History. We have used the TPS54040 for years but switched to the TPS54360 earlier this year. Have not had any problems at 30 volts

    Not sure if your can view pcb  or cam files but here is a pdf. The red layer is top with full ground plane under part.0143.tps54360.pdf

  • Hi John,

    At which point are you measuring the input voltage? There is a pretty long distance from the input capacitor to the TPS54360 VIN pin. It would be best to measure the voltage directly at the VIN pin. If it is possible I also suggest trying to solder down a ceramic capacitor from the TPS54360 VIN pin to the GND pad of the schottky diode D5.

    In addition to the distance from the VIN pin to the input capacitor, the series resistor R131 could be reducing the effectiveness of the bypass capacitor. I recommend trying to solder a short wire across this to short it and see if there is any change.

    Best Regards,
    Anthony