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Original question:

TPS54331 failing

TPS54331: Failing as short circuit on output

Peter Diamond
Prodigy 10 points
Part Number: TPS54331

Hi there for some reason I've had two of my power converters fail either as the Vin pin blowing up or the output short-circuiting inside of the IC. I am running this off of a 20V battery and regulating it down to 5V. I will note the battery is connected via a switch that controls power to the whole board. The system seems to work at first, but after turning the system on and off a couple of times it fails. I based all of mydesigns around the design tool, so I'm not really sure what's happening. Here is my schematic, PCB Layout, and simulations

  • 0
    TI__Genius 15135 points

    Hi, Peter 

    1. I review the schematic, the problem is at C6, it should be 100nF, not 10nF. 

    2. D1 is very small, does it can bear 3A loading? 

    If still have problem, suggest probe some waveforms including Vout, PH, inductor current when issue happening. 

  • 0
    Prodigy 10 points

    I noticed that before doing my testing and replaced that capacitor. Also, my diode is rated for 3A. I'm hoping to get access to an oscilloscope soon, but I'm hoping there are some suggestions about where the issue is coming from. Would a transient on the Vin cause the output to short circuit?

  • 0 in reply to Peter Diamond
    TI__Genius 15135 points

    Hi, Peter 

    As long as transient on the Vin is not larger than abs max rating voltage, it will not cause Vout short circuit.  

    Please replace the C6 and do the test, and capture the waveforms if issue is still happening. 

    If there are no issue waveforms, I cannot analyze the root cause. 

  • 0
    Prodigy 10 points

    Hi the issue has been resolved. Due to inductances of longer wires coupled with the low input capacitance as well as some switch bounce, there was some oscillation on the input. This created spikes that reached >40V which would blow up the IC. By increasing the input capacitance to 150uF (could possibly go lower) the issue was fixed. Ignore the blue waveform in the spike picture as it was hooked up to the same spot as the yellow