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LM5122: How to decrease the overshoot on SW signal?

sun qiyun
Intellectual 280 points
Part Number: LM5122

Tool/software:

Dear

I am designing a boost circuit from 24V to 48V, output current is 5A. I test the SW and find it having a little overshoot. the waveform below.

I also test the ripple, it is also a little bigger, waveform below.

The schematic is below. Could you please help give some suggestion for improving them? Thanks in advance.

  • 0
    TI__Mastermind 30030 points

    Hello Sun,

    Thanks for using the e2e forum.
    To reduce the switch node overshoot, the first step would be to increase the gate resistance (R87, R146). Adding resistance in the range 1 Ohm - 10 Ohm can already reduce switch node overshoots significantly.

    The next step would be adjusting the RC snubber to increase the filtering effect.

    If none of these solutions can reduce the overshoot enough, the final step would be to review the layout and find optimizations here.

    Regarding output voltage ripple, low ESR ceramic capacitors are best for filtering switching noise.
    However, adding more ceramic capacitors may also require a layout change to add the required footprints.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    Intellectual 280 points

    Thanks Niklas.

    I will try.