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LM5010: Is this part short circuit safe?

eric jensen
Prodigy 90 points
Part Number: LM5010

The short protection circuit for LM5010 is a bit unusual - looking at off-time flyback current to turn off transistor not on current cycle but on next cycle.  In practice, is this part short circuit reliable?

  • 0
    TI__Mastermind 25590 points

    Eric,

    Yes the LM5010 will react to an over-current condition when it senses the condition during the off-time. This means current can ramp up during one switch cycle before the condition is sensed. This is not likely to be an issue if considered during component selection. From the datasheet, "If that current exceeds the threshold the current limit comparator output switches to delay the start of the next ON-time period." This prevents runaway and keeps the peak current down. You can calculate the worse-case max current by using the on-time and the voltage across the inductor which, worst case, would be VIN. Make sure this peak does not exceed the saturation current of the inductor and the circuit should be fine.

    -Sam

  • 0 in reply to Samuel Jaffe
    Prodigy 90 points

    thank you for the response. At what peak current (over duration of cycle) does the switch fail?

  • 0 in reply to eric jensen
    TI__Mastermind 25590 points

    Eric,

    The switch should not become damaged due to the nature of the current limit unless the absolute max specs are violated.

    -Sam