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LM3409: LM3409QHV how to work with TPS92662Q1 reliably

Jarod
Prodigy 100 points
Part Number: LM3409

Dear Sir or Madam,

When I plan to use LM3409QHV as constant current source to work with TPS92662Q1, I faced the some questions.

The details of issues were described in attachment.

I'm looking forward to your reply.

Thanks! JarodLM3409QHV.pdf

  • 0
    TI__Mastermind 25500 points

    Hello Jarod,

    I can answer these questions for you. Please give me until Monday when I'm back in the office and I will respond. Thanks.

    Regards,

    Clint

  • 0
    TI__Mastermind 25500 points

    Hello Jarod,

    To answer your questions:

    1. I would give at least 20% headroom for I_sat over the peak current you are setting.

    2. That is fine. You have plenty of headroom over the minimum. running at the minimum is fine as well.

    3. The LM3409 was designed for this type of dynamic load so it will be fine. Design for all LEDs on and it will work with the lower LED stacks when some or all LEDs are off.

    4. Your understanding is correct. The values may need to be adjusted slightly on the bench to fine tune the ripple. You want the peak-to-peak inductor current ripple to be the same with all LEDs on as it is with all switches on (LEDs off).

    Regards,

    Clint