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Why LM3478 gets hot?

Fan Yi
Intellectual 280 points
Other Parts Discussed in Thread: LM3478, TPS54160

Hello,

I tried to use LM3478 boost to convert 24V input into approx. 31V output. Then use TPS54160 to regulate out a floating charge voltage for lead acid battery.

This scheme seemed to work, but LM3478 got hot at about 72 Centigrade which I think is abnormal.

See the attached schematic. V5 is SUD40N10-25-E3 from Vishay.

I can not figure out what went wrong. Could you help to identify it? Thanks.

  • 0
    TI__Genius 10115 points

    R6 which sets the switching frequency is current set for a switching frequency near 3MHz.

    Lower the switching frequency to something closer to 500Khz and you will improve the thermal performance of your design. You will probably need to recalculate your compensation components after changing the frequency.

    Regards,

    Marc