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TPS548A28: Test problem

Yadong Duan
Intellectual 1200 points
Part Number: TPS548A28

Hello, I found that the waveform of PGOOD has a large ripple during the test startup process. What caused this? Secondly, during the startup process, the output voltage has very small spikes. Is this a problem with my test environment?

Dark blue is the input voltage, light blue is the EN voltage, pink is the PGOOD voltage, and green is the output voltage

  • 0
    TI__Mastermind 23580 points

    Ch2, Ch3 and Ch4 do not have the bandwidth on. Ch1 does have the BW on.

      I believe the Ch2, Ch3, Ch4  channels are picking up the converter switching.

    The ripple you see on Ch4 from 0 volts to the time PGOOD transitions high is the converter switching.

    I think the device is configured for skip operation and device stops switching for a short time ~1ms after the PGOOD is high.

    The device once switches once or twice.   You can probe the SW node and check if the ripple corresponds to the SW switching.