Capacitors vs buck/boost converters


I'm trying to drive high power LEDs with a laptop power supply, and wondered if I should use resistors to limit the extra current, or something like this to limit the current. If I did use that module, I would run it at 55V @ .7A

I'm aiming for decent efficiency without designing my own module. The laptop power supply I'm using is rated at 19.6V @ 4.62A. From there, I could either use a (cheaper) boost converter like this, which only limits voltage, and from there use resistors to limit the current. Or I could use the more expensive first linked module to regulate current and voltage. Which is better, in terms of efficiency?

I feel like the boost converter would be more efficient, but everyone else's circuits use resistors to limit current. Is there something I'm missing?

If I've made any incorrect assumptions, please tell me. I want to make sure I do this well.

Best Answer

Use a current regulator.

A voltage regulator won't do as LEDs change their resistance when they get warm and thus needs different voltage to get the same output from them. If you use a resistor you will just burn Watts and make a nice oven, even at 700mA. current regulators are the way to go, don't cost too much and will be most efficient as you don't need any resistors and. And if you want to be very efficient, select a switching current regulator... It would be also a good idea to have the input voltage as close as possible to the LED(s) voltage.

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