Building A Driver For Absurdly High Power LEDs

A few years ago, the highest power LEDs you could buy capped out around three watts. Now, LED manufacturers are taking things to ridiculous power ratings with 30, 40, and even 90 watt LEDs. Getting these high-power LEDs are no longer a problem, but powering them certainly is. [Thomas] built a LED driver capable of powering these gigantic LEDs and creating a light show that is probably bright enough to cause bit of eye damage.

[Thomas]’ LED driver is based on Linear Technology’s LT3518 LED driver. This driver is part of a project to build a huge WiFi controlled RGB LED, so the driver has outputs for three separate LEDs capable of sourcing 700 mA each.

Because [Thomas] is dealing with crazy amounts of heat and power required to light up these huge LEDs, the driver board features a temperature sensor next to each LED driver. When the board gets too hot, the driver automatically shuts down, preventing bad things from happening.

You can check out a few pictures of [Thomas]’ LED driver over on the build page for his WiFi LED project. A truly awesome amount of lighting power here, that also makes it impossible to get a good picture of the board in operation.

26 thoughts on “Building A Driver For Absurdly High Power LEDs

      1. KIS-3R33S modules are available absurdly cheap from ebay sellers.

        They handle 3A and are happy being PWMed by their enable pins. They are strictly constant voltage rather than constant power and tend to smoke if you try to modify them at all, so you have to waste a little power in a ballast resistor. They’re still the simplest solution and better than a linear reg.

      2. @Nes: You can avoid the power-wasting ballast resistor. I’ve figured out how to easily turn these modules into constant-current LED drivers.

        Set the voltage to just above the maximum voltage you’ll need. Put a low-side sense resistor between the LED and ground. Use one of the four comparators from a LM339 to output active low when the voltage across that resistor rises above your desired threshold. Connect that output to the MP2307’s soft-start pin (or the external capacitor connected to it) through a 10k resistor. And you’re done.

        The soft-start voltage acts as a multiplier for the final output voltage. It rises linearly via the chip’s internal 6uA constant current source, up to a maximum of 0.985V. But if the current exceeds the threshold, the comparator adjusts the soft-start voltage (and thus the final output voltage) down, until the overcurrent condition no longer exists.

        I wouldn’t consider this a precision current source, as the actual current may oscillate a bit; but not enough to affect LED output or reliability. If for some other reason this oscillation is undesirable, it can be reduced by increasing the value of the 10k resistor, taking care to ensure the comparator can still pull the voltage low enough to maintain regulation.

        As a bonus, the remaining three comparators can be used for three more channels. ;)

    1. Acer K330 LED, 3D, 720p, Projector. 500W Phatlite LED’s should last 20-30,000 hours (normal led TV’s are rated 40,000hrs)

      The best $500 I’ve ever spent!! 132″ TV/Movie/PC/Xbox/etc

  1. I don’t get it. It’s a design for a not so powerful driver, obviously not able to power a 30-90W LED. With only 700 mA, it’ll be able to light strings of 3W LEDs, no more.

  2. About a year ago I was part of a team building a 7kW array of LED heater for a vacuum chamber. Blue 300W LEDs with water cooling where used to heat some silicium(silicone) wafer. Infra is going trough silicium so the physic told us to use blue LED instead. Other machines where 10kW and above with special heating lamps. So it was realy a thing where energy could be spared.

    I was responsible for the SW which was implementing a PID controller and driver stages for the LED. Each LED could be controlled separately to compensate heat differences. Also some failsafes where implemented. Each LED water cooling temperature was measured and check if it is not too hot.

    We could measure the voltage and current of each LED array. First we tried to turn on each LED a little bit, then a bit more, and more. Then all LED togethet a little bit. Always checking how much of the LEDs got damaged in the array. Yes, some LEDs got damaged (ESD, or was already shipped damaged) but not the whole array. Finally after some week of redesigning we have got the permission to turn to full power. Playing with so much LEDs isnt cheap, so noboody wanted to do irreparable damages and extra work.
    So for the first time I removed the power limit from the SW and we pushed up the slide for maximum power. Then we reached 6,8kW, it was unbelivable. No explosion, no overheating just everything was blue. Temperatures where stable.

    Turning on so much LED was really funny, because everything was painted with blue. We had some glasses to check if the LEDs are OK, but I do not need to say that it was so hot like the sun in summer.

    On the silicium(silicon) 412 Celsius degree where measured. Full success.

  3. I want to see some DIY for LED car headlight and projector / rear projection TV bulb replacement.

    I have a nice digital LCD projector and am dreading when the bulb dies. I know it’s possible to hack the thing to not need to detect the bulb lighting.

    Eliminating the high voltage to the bulb makes a projector use much less power.

  4. I wonder what would happen if you took one of these super high power LEDs, and pulsed it with 100A for 1nS? Would it hold up? Could you use this LED flash lamp to pump a laser medium? Most of these hogh power LEDs take 700mA contimuiously. Now take that LED and hit it with 100A for 1 nS, what would the the light output flux on that? I bet it would be like a nuclear blast going off. Definitely wear eye protection.

  5. I am wanting to know if there is a power supply I can buy to drive a 500 watt LED chip I’ve bought, I only want to drive it at half its rated power i.e. 250 watts, but trying to get a power supply at 70 to 78 volts at 3.2 Amps is virtually impossible it seems to defy OHMS law the full chip spec is 70 to 78 volts @ 6.9 to 7 amps.

    I would be more than willing to pay some one to build one!!.


  6. Hi there
    To anyone out there, I have bought a 500 watt LED chip, and don’t seem to be able to find a power supply for it, I’ve scoured the internet,(no results) the problem is OHMS law!! in an ideal world I would like to buy a power supply that I could vary the wattage from 0 to 500 watts, I don’t think that’s going to happen. The chip spec is 70-78 volts DC @ 6.9 AMPS.
    But I only want to drive the chip at half power 250 watts for the longevity of the chip. Does anyone know where I could buy a power supply from or if any one knows a DIY genius that could build me one I’m offering £200 I know its not a lot but its for a one off project.

    1. I know the chip you mean and I contacted the supplier( via ebay)and even they couldn’t help ! It seems to me that it would require taking the biggest driver circuit that you can find and then multiplying the power output circuit several times as is done on many power audio amps .Sorry this is not much but it might point you in the right direction. Paul.

  7. @Nes: You can stay away from the power-squandering balance resistor. I’ve sorted out some way to transform these modules into steady momentum LED drivers without any problem.

    Set the voltage to simply over the greatest voltage you’ll require. Put a low-side sense resistor between the LED and ground. Utilize one of the four comparators from a LM339 to yield dynamic low when the voltage across that resistor transcends your ideal edge. Interface that result to the MP2307’s delicate beginning pin (or the outer capacitor associated with it) through a 10k resistor. What’s more, you’re finished.

    The delicate beginning voltage goes about as a multiplier for the last result voltage. It rises directly by means of the chip’s interior 6uA consistent current source, up to 0.985V. In any case, on the off chance that the current surpasses the limit, the comparator changes the delicate beginning voltage (and in this manner the last result voltage) down, until the overcurrent condition does not exist anymore.

    I wouldn’t look at this as an accuracy current source, as the genuine current might sway a little; yet insufficient to influence LED result or dependability. If for some other explanation this swaying is unfortunate, it tends to be decreased by expanding the worth of the 10k resistor, taking consideration to guarantee the comparator can in any case pull the voltage sufficiently low to keep up with guideline.

    As a little something extra, the excess three comparators can be utilized for three additional channels. ;)

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