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TPS92410 simplified driver

Davey Hudson
Prodigy 40 points
Other Parts Discussed in Thread: TPS92410, TPS92411, TPS92561

I'm looking for a simple circuit to drive strings of LEDs that require 160v @ 100ma. The TPS92410 looks ideal but I'm wondering if the TPS92411 drivers could be omitted and just have the TPS92410 drive the entire string? The LEDs are part of an assembly and it would be difficult to tap into the middle of it to use the TPS92411s.

Or is there a better solution with low component counts and inductorless?

Thanks!

  • 0
    TI__Expert 3495 points
    Davey:
    You can not use TPS92410 without using TPS92411. The 160V LED string needs to be broken to sections. If it is not possible to break the LED string, I suggest using TPS92561 boost which is simple but not inductorless.
    David Zhang
  • 0 in reply to David Zhang
    Prodigy 40 points
    The TPS92410 seems to be completely independent of the TPS92411s. It doesn't send nor receive any signals to/from them. All is sees is the LED chain current and all it does is control the gate of the external power MOSFET to regulate that current.

    If my understanding is correct, the upper TPS92411's will shut current around part of the string to keep the lower sections of the string illuminated during valleys in the AC voltage. I think that this would produce uneven illumination across the string which is extremely undesirable in my application- photography lighting where one of the advantages of LEDs is even illumination by spreading the light over a strip rather than a tungsten point source.

    If the concern is about turn-off around zero-crossing, I could add capacitance to the input- essentially drive it from DC.

    The TPS92561 is a boost regulator so how could it be used to drive a 160v string when the line voltage peak (~165v) will exceed that?

    Thanks!
  • 0 in reply to Davey Hudson
    TI__Expert 3495 points
    Davey:
    If you use TPS92410 to drive 160V LED string, the LED is on only at the peak voltage when Vin > 160V. If you want to use an input capacitor to keep the voltage above 160V, the cap is going to be very big and the voltage is still lower than 160V at low line 108Vac.
    You are right. The peak input voltage exceeds 160V. So the boost topology is not a good chocie. You may need to use a buck boost solution.
    David Zhang