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LM3409HV: LM3409HV dimming response time

Tom Li53
Prodigy 290 points
Part Number: LM3409HV
Other Parts Discussed in Thread: LM3409

Hello，

My customer is pan to use LM3409HV for a 150W lighting power. The output is about 45V/3A at full load. Now they are asking about if use analog dimming, what's the response time when LED current change from 0.1A to 3A. Will it be less than 50uS? Please help for confirm it. Thanks!

  • 0
    TI__Mastermind 25500 points

    Hello Tom,

    The LM3409 is very fast and will react to any change in the IADJ voltage the very next ON cycle. So it depends on how fast the IADJ voltage is changed, but assuming it goes from min to max in one switching cycle the only delay is the extra rise time to the higher peak current dictated by v=Ldi/dt. So the rise time depends on the inductor value and the input/output voltages. In any reasonable case I can think of it should be much less than 50us assuming it is not limited by the IADJ voltage slew rate.

    Regards,

    Clint