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TPS54240: TPS54240

Genie Hsu
Intellectual 360 points
Part Number: TPS54240

Dear sir,

I used "PS54240EVM-VSON Regulator Evaluation Module" to do my experiment. I randomly repeatedly plug and unplug input at VIN terminal, I found there was a high voltage at VOUT (up to 6.2V).

The output of this evaluation module is 3.3V. My question is how to solve this high voltage.

Channel 1 (yellow) showed input power (12V), channel 2 (blue) showed output waveform, and channel 3(pink)  was measured at PH terminal. 

  • 0
    TI__Mastermind 23845 points

    Hi,

    Are you referring to 6.2V spike on the output which is the blue waveform?

    It seems that the spike is not aligned with the PH node waveform, do you have anything else that might be causing this noise?

    Could you just probe the output voltage by itself and see if there is still a spike there? (Disconnect the pink and yellow waveform)

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Intellectual 360 points

    Dear Sir,

    Yes, I mean the blue waveform in my previous posted waveform.

    I probed output waveform alone this time, spike voltage is much smaller than before, but I still can get a voltage higher than 4V at output.

    In reality, there are some parts got damage in my project, I am not sure if it was caused by this spike.

  • 0 in reply to Genie Hsu
    TI__Mastermind 23845 points

    Hi,

    It seems like there might be something else in the system that causing this spike because it is not aligned with the PH node. Normally switching noise from converter is related to the PH node rising and falling edge 

    Can you disable the TPS54240 part and check the output voltage and if you still see this spike?

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Intellectual 360 points

    dear Sir,

    I connected enable pin to ground and measured output (channel 1) and input (channel 2) waveform.

  • 0 in reply to Genie Hsu
    TI__Mastermind 23845 points

    Hi, 

    It seems that there could be some coupling from the input? 

    Is there a way to reduce spike on the input? Maybe try to slowly ramped the input voltage?

    Another way to reduce noise at the output is to use a ferrite bead at the output as a secondary filter or use a post regulator such as an LDO

    Thanks

    -Arief