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TPS56528: When Start up Output current have inrush current .

WU YISYUAN
Expert 2165 points
Part Number: TPS56528
Other Parts Discussed in Thread: TPS54528

Hi,

     I measure my circuit find the output current have inrush current at start up.

    But I saw datasheet just define current limit, not define inrush current.

    As I know, if output current is so high, that PIN SW might be higher.

    Could show SW PIN max current, or have inrush current define?

    In my circuit, the start up current is 7.04A, have any risk?

   test condition:Vin=12V, Vo=5V, Io=1.5V.

thanks.

  • 0
    TI__Expert 3480 points
    SW PIN don't have max current limitation. Only when inductor has larger ripple, IC has risk of damage in high Vin case.

    Can you help test the startup waveform for SW, Vo, inductor current.
  • 0 in reply to Gavin Wang (Zejing)
    Expert 2165 points
    Hi Gavin,
    You mean SW PIN has no current limit?
    I need to know that how many withstand current in SW PIN and VIN pin.

    thank.
  • 0 in reply to WU YISYUAN
    TI__Mastermind 27470 points
    Hi YISYUAN:
    for the start up current rush, if I understand rigth, it is output current. If I am wrong, pls correct me.
    for DC/DC output current , it is decided by the load . so you can check whether your e-load has certain current overshoot when Vo raising.

    and second, if the load truely sink 7.04A current at start up , based on TPS54528, it is safe becasue our typical OCP spec is 6.2A which is also the typical current go though low side mosfet . and With your inductance, the typical OCP of output current is 6.68A(8.28Max).

    and we strongly recommend checking the loading current start up by extenral source, as metioned before, it is decide by your load. sometime, CC(constant current) mode of E-load will have such overshoot current. Change to CR(Constant resistor) will help.

    Thanks
    Daniel