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LM3409-Q1: LM3409 application note 2 pspice simulation problem

park tae hyun
Prodigy 20 points
Part Number: LM3409-Q1
Other Parts Discussed in Thread: LM3409

i used pspice LM3409 application note 2 

but i have problem initial voltage & current peak is very high, I don't know why this is happening.

LM3409.pptx

  • 0
    TI__Mastermind 28655 points

    Hello,

    When the simulation starts Vled and Iled should be zero and the first off-time pulses should be long not short.  Yours are short.  What are your initial conditions set to?  You need to look at other points in the circuit to see how the simulation started and what it is doing.  The first pulses leave the on-time to short so the LM3409 will put out a minimum on-time which is longer causing the current to be higher (look at the switch node in the simulation).

    Best Regards,