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LM5148: Find a solution with dual level current limit

Cindy Chang
Intellectual 2475 points

Part Number: LM5148
Other Parts Discussed in Thread: TPS25985,

Hi experts,

We are finding a solution which has programmable current limit and delay time for my 1st current limit point, the 2nd current limit point will immediately react when is senses the current limit is tripped and will pull VOUT to 0V.

The input voltage would be from 19V to 24V, and output voltage would be step down to 12V.

The 12V rail has a nominal current limit of 15A(1st current limit point) and a critical current limit at 33A(2nd).

Both current limit should activate but the 15A will have a delay and pull output to 0V when the current limit threshold meet.

For the 33A threshold, the current limit should trigger immediately and cutoff the output voltage and let output to 0V.

May we know that is there any solution could fit this requirement?

Thank you.

Best Regards,

Cindy

  • 0
    TI__Mastermind 22302 points

    Hi Cindy,

    It sounds like you want to use an eFuse, especially for the 30A case to shut down instantly.

    Check out TPS25985, I think it's more suitable.

    You'd set the 30A as the hard limit, and then probably have to use the IMON function and some external circuit to get the 15A limit and delay.

    LM5148 current limit is peak inductor current cycle-by-cycle limiting, it will limit inductor current to a setpoint, say 15A, indefinitely, for a weak overcurrent.

    In a strong overcurrent where the output voltage falls to less than 50% of setpoint, the hiccup mode function enables, which is 16384 cycles of this condition then triggers a restart.

    It would never instantly shutdown when a current limit is hit.

    Also only inductor current is limited, there is still output capacitors than can supply large current for a short period of time.

    Hope this helps,

    -Orlando