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Original question:

LM25069-2 when there is overcurrent it disconnect and doesn't turn on again

LM25069: LM25069 damaged in short current test

Robin Liu
Intellectual 1930 points
Part Number: LM25069

Hi team,

As my customer use LM25069 as the overcurrent and short current protection device, but we find the device OUT pin is easy to be damaged, and we find there is a negetive spike voltage(<<0.3V) when do the short current test.

I go thru your old E2E threads, you recommended to add a 1k resistor on the OUT pin and a shotkey diode in parallel. We do so, it works in 50A current, but because the customer actual design demand is to protect a 100A overcurrent, then the dI/dt would be very big. then the OUT pin still would be damaged.

I want to know, if we replace the 1k resistor with a diode is a good idea to prevent the negetive spike goes lower than 0.3V under the worst scenario? Thanks.

Regards,

Robin Liu

  • 0
    TI__Guru** 105361 points
    Hi Robin,

    Schottky diode is needed to clamp the o/p voltage going to -ve side during fast cut-off events.

    Can you please share below information to understand the issue
    1. test waveform during overload event
    a. Vin, Vout, GATE, Timer
    b. Vout, GATE, Timer, input current
    2. test waveform during short circuit event; Vin
    a. Vin, Vout, GATE, Timer
    b. Vout, GATE, Timer, input current

    Best Regards,
    Rakesh
  • 0
    TI__Guru 57737 points

    Hi Robin,

    As mentioned in the datasheet, a schottky diode is required for inductive loads.

    A schottky diode which has 'Peak Forward Surge Current' greater than the maximum fast current  trip threshold of your design needs to be selected.