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TPS92512: TPS92512 flickering problem

Prodigy 120 points

Replies: 18

Views: 421

Part Number: TPS92512

hi,

i am using TPS92512 ,for dimming  purpose

i am using 24v supply and 4 X20 led matrics (4 series)

i get the flickering during the period when current in between 600mA and 800mA

i am using the same circuit given in the data sheet please give me a solution

total voltage 24

volatge across led 11V

no of led series 4 

  • In reply to Irwin Nederbragt:

    vin when pwm is applied & we are not using any emi filter

  • In reply to Jishnu Prakash Nambiar:

    Hello,

    Okay, so what does the SW node and output/inductor current look like now? Vin needs to be solid and stable to have an output current that is also stable.

    Best Regards,
  • In reply to Irwin Nederbragt:

    hi,
    now the flickering issue is solve but , it takes some time to reach the designed maximum output current
    i designed for maximum 680mA but when i switch on the device for first time it only reaches maximum current of 280mA
    then over time i reaches maximum designed current
  • In reply to Irwin Nederbragt:

    also what kind of thermal relief you would recommend,
  • In reply to Jishnu Prakash Nambiar:

    Hello,

    What is the time constant of C2 and R3? If this is not the reason I would measure the input and output voltage to make sure they aren't close together. You have 24V input and 11V led which should be fine. Make C2 a much smaller value, maybe 100 pF which should speed up the current set-point

    Not sure what you mean by thermal relief? The datasheet will have recommendations for PCB layout. Page 21 of the datasheet shows an example.

    Best Regards,
  • In reply to Irwin Nederbragt:

    hi,
    can you suggest another chip for our purpose,
    we are hopping here to develop a led driver which can drive up to 20 w
    at 24 v, we need pwm to analog dimming method
  • In reply to Jishnu Prakash Nambiar:

    Hello,

    Have you tried changing the time constant on Iadj?

    There are a lot of parts that will work, TPS92515, TPS92640/641, LM3409, TPS92512/13.

    Best Regards,
  • In reply to Irwin Nederbragt:

    thank you

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