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LM5118: Output unstable

Kuan Wei Chen (Kevin Chen)
Genius 9710 points
Part Number: LM5118

Dear Team,

The customer use LM5118 for PD input and boost to 54V for PSE output.

During room temperature, the device works fine.

But during 45dC operation will have below issue

1. Vin: 41.1V, Vout: 54V, Load: 0 ~ 55W Normal
2. Vin: 42V, Vout: 54V, Load: 48W plus 12W Normal
3. Vin: 41.1V, Vout: 54V, Load: 48W plus 10W Normal
4. Vin: 41.1V, Vout: 54V, Load: 48W plus 12W. The following waveform appears.

BR

Kevin

  • 0
    TI__Mastermind 21720 points

    Hi Kevin,

    Thanks for reaching out with your question and for using the LM5118.

    It looks like the LM5118 is hitting peak current limit and triggering the hiccup mode operation. Can you please probe UVLO and see if it is getting pulled low?

    Also, what is the value of the selected inductor? I typed in the part number but was not able to find it online.

    Let me know if you have any questions.

    Thanks,

    Garrett