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LM3150 & LiPo battery

Eric Plantier
Prodigy 30 points
Other Parts Discussed in Thread: LM3150

Hello,

We have designed a DC/DC converter using the LM3150 to generate a 2A 13V power rail from a 24V Lipo battery. This 13V power rail is used to feed an external load (pump) and to generate all the system power rails (10v, 5v and 3.3v).

When we test this solution with a laboratory power supply, results are good : we have an output voltage of 12.9V and we can deliver 2A to the external load and supply all other system power rails without heat increase or output voltage drop. We made the test with input voltage values from 20 to 32V.

Problem is if we feed the system with the Lipo battery (@ full charge Vbat = 28.8V), the LM3150 is irremediably destroyed (component explosion with smoke). We have performed the test on 2 boards with same results.

please find the schematic of the LM3150 power stage.

6545.SCHEMATIC1 _ Power Supply.pdf

I hope someone can help me to find a solution !

Thanks,

Eric

  • 0
    TI__Intellectual 770 points

    Hi Eric,

    Please do you have plots showing the turn-on events for both the battery and the power supply?

    The soft-start time should be greater than the input voltage rise time; which will reduce the start-up stresses and control the inrush currents. I suspect the Lipo battery turn-on time is much faster; which can lead to a very high inrush current that may damage the part.

    Regards,

    Doyel

  • 0 in reply to Doyel Ghosh
    Prodigy 30 points

    Hi Doyel,


    Thanks for your reply.

    Unfortunately, we don't have any plots.

    We will try to increase the soft-start time (once we replace the damaged part !!) by changing the Css capacitor to 150nF. This will give us Tss = 11ms. Could we have problems if the soft-start time is too slow ?

    Regards,

    Eric

  • 0 in reply to Eric Plantier
    TI__Genius 15810 points

    Hello Eric,

    1ms of soft-start might be a little too fast and if the battery is providing all its charge then there could be a very fast current spike that could cause damage. I don't think there's issues with a larger soft-start time. Hope this helps.

    Regards,
    Akshay

  • 0 in reply to Akshay Mehta
    Prodigy 30 points

    Hello.

    We have changed the Css value to have a 50ms soft start time. And it works fine.

    Thanks a lot for your help.

    Best regards,

    Eric