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TPS54231: excessive ripple voltage

Part Number: TPS54231

Hi support team,

attached pictures is schematic and output waveform in different loads. pls  suggestions for improvement. thanks.

  • Hi,

    You want to reduce the output ripple, right? The output capacitor is electrolytic capacitor, it is reasonable that the ripple is large. You can try to add a 22uF ceramic capacitor to reduce the ripple.
    For the last waveform, what are the test conditions? It would be better to add SW waveform for better understanding.

    Shawn
  • Thank you Shawn.  test conditions:  1: 13.5V1.3A IN, load 0.7A. 2:1: 13.5V1.3A IN, load 1A. 3:1: 13.5V1.3A IN, load 1.3A

  • Hi,

    The max input current is 1.3A, right? For the application of 13.5V->12V/1.3A, the input capacitor voltage may be lower than 13.5V because of the large load current, please try to use the power supply with greater output ability to check this issue.

    In addition, Maybe the BOOT UVLO is triggered, please test the waveforms (VIN, VOUT, SW, BOOT) to double check it. Please refer to below application note to understand BOOT UVLO.
    www.ti.com/.../slua928a.pdf

    Shawn
  • Thank you Shawn, i changed input capacitor 1000uF to 4400uF,The ripple of the output voltage is decreased remarkably.  Attached are test input ripple Vpp (blue channel 3), SW voltage test (green channel 2), output ripple (yellow channel 1).   1: Input 2A, Load 1.8A , capacitor 4400uF.   2 :Input 2A, Load 1.3A , capacitor 4400uF.  3 :Input 2A, Load 1.8A , capacitor 1000uF. 4 :Input 2A, Load 0.7A , capacitor 1000uF