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LM5176: LM5176 only works when I touch the capacitor with my hand

Zheng Hao Chin
Prodigy 50 points
Part Number: LM5176

Tool/software:

I have designed a dc-dc  converter using the LM5176. However, when I connect it to power, it is only able to work if I touch my finger to the capacitor on the comp pin. I am assuming that this is due to the extra capacitance brought by me touching the capacitor on the comp pin. I would like to request a review of my loop compensation values and layout.

LM5176 Buck-Boost Quickstart Tool.pdf

Schematic

Layout (Pin 1 is on the bottom left)

Thank you!

  • 0
    TI__Genius 15575 points

    Hi Zheng,

    Thanks for reaching out.

    How does you circuit behave with and without you finger on the COMP cap? Can you maybe send some scopehots of Vin, Vout and both switchnodes?

    I would recommend to go lower with the crossover frequency (to 45-50kHz max.)

    Best regards

    Moritz