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LM5018: current limit feature

Guru 28375 points
Part Number: LM5018

Hi Team,

Is the current limit feature of LM5018 foldback feature as the following?


Best Regards,
Yaita / Japan disty

  • Hello Yaita,

    The LM5018 has a peak current limit and an off time generator when the peak current limit level is violated. The result is, the current to the output will be averaged between the peak current limit level and the inductor valley current reached, during the off time. The result is that the LM5018 current limit will cause the current to foldback a little.

    Hope this helps?

    David.

  • Hi David-san,

    Thank you for your kind support.

    >The result is that the LM5018 current limit will cause the current to foldback a little.
    Is there any solution to expand the amount of foldback curve?

    Best Regards,
    Yaita

  • Hello,

    The output current whilst in current limit is set by the peak and the valley current limit level, set by the Off time generator. A smaller peak to peak ripple current in the inductor (Delta IL) as a percentage of Iout will increase the fold back current in current limit.  i.e. if you make you inductor larger, or increase the swtich frequency, causing a large drop in output current when in current limit.  You could run a quick test to see this.  Short the output and measure Iout when in current limit.  Then increase your inductance and do the same test, you will see the output current reduce when in current limit.

    Hope this helps?

    David.