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LM3409HV: None

Jaideep Dharia
Prodigy 10 points
Part Number: LM3409HV

I have a 10usec pulse inputted into the Enable pin and DAC voltage inputted into pin 2. After being on the field for two years we are seeing jitter at the output of the 10 usec pulse. This jitter causes light flicker.

Any ideas what I should be doing

  • 0
    TI__Mastermind 25500 points

    Hello Jaideep,

    Are you saying it worked fine for 2 years but it isn't now? Is the control (pulse width, timing, etc...) the same if so?

    How long do you have between your 10us pulses? I ask because when EN is pulled down VCC is allowed to discharge. When it hits the UVLO threshold the part goes into low power shutdown mode so it responds slowly to the next pulse and will go through a startup sequence. Depending on where VCC is at when EN is pulled high it could behave differently from cycle to cycle if the frequency is right. If this is your case you can use the UVLO pin to PWM dim exactly like you use EN but VCC will not discharge so it will react very quickly and predictably to every ON pulse.

    If not could you capture some waveforms of the pulse and the LED current when this is happening?

    Thanks,

    Clint