High Power Light Emitting Diodes have different requirements that need to be met when compared to regular LEDs. This guide will provide all the knowledge to power whatever High Powered LED you come across but will focus on 3W Aluminum Backed Star LEDs.


The average LED is great for adding status indicators to your projects or for splashing around some colors with an addressable strip however an individual standard LED is not very bright, high input LEDs, on the other hand, can produce intense amounts of light in a form only a little bit larger than a standard LED unit the catch, however, is that high-power LEDs have different requirements that need to be met when compared to their regular LED cousins.

Hey gang! Tim here at Core Electronics and today we're covering how to use these three-watt high-output LEDs with a dc to dc step down converter let's get started. It is not practical to regulate the current of high-power LEDs using only resistors as a lot of energy is going to be wasted to heat and it can easily lead to thermal runaway so it is vital to use an LED driver with a switched mode voltage and current regulation high output LEDs also generate significantly more heat which must be drawn away with a heat sink to prevent overheating damage from occurring.

In this guide we will figure out and select the right gauge of wire manage heat dissipation and power requirements. If you're new to the world of LEDs check out our crash course or if you're just looking to use some addressable rgb lights we have the guides for you links are down in the description. In this video I'm going to power a single 3 watt LED and then I'm going to power 4 of these LED nodes in series our system here is going to be a simple full power on or off we won't need a microcontroller with the setup that we create here if you do want the ability to dim the LEDs then you need an LED driver with dimming capabilities or you're going to have to utilize a microcontroller.

On the table before me is everything you're going to need to set up these 3 watt LEDs naturally you're going to need some star LEDs these get hot so it's good to have some heat sinks for them these Raspberry Pi heatsinks are absolutely perfect. You will also need a dc wall supply here I'm using a 12 volt 2 amp one you're going to want a dc barrel jack adapter to make connecting to the step-down converter easy, this step down converter here is a dc to dc adjustable step down module capable of pushing out 75 watts, I will also attach this toggle switch to our four node LED system.

To connect all the parts up you're going to want to use 18 awg wire as this is the perfect thickness for the job in regards to tools you're also going to need a multimeter and you're going to want a little screwdriver to aid in adjusting the step down converter. The amount of light that an LED emits depends on how much current is supplied high-power LEDs commonly take currents from 350 to 3000 milliamps from the data sheet we can find that each node of these three watt red LEDs here desire 750 milliamps at 2 to 2.8 volts.

If we were to connect this standard dc 12 volt power supply directly into this LED it would provide too much current to it and cause this LED to break this is why we need a constant current LED driver between the dc power supply and the LEDs. The most appropriate LED driver for this and most applications would be a buck or boost converter, these are also known as step down or step up modules. Importantly for LED driving applications these manage and prevent excess current flow these LED drivers normally provide a range of voltages and currents which can be altered to precise levels by adjusting these potentiometers. So let's set up the LED driver correctly to power a single 3 watt red LED node which we know from the data sheet requires 750 milliamps at 2 to 2.8 volts.

Before connecting up any LEDs do the following connect up the dc to dc adjustable step-down modules inputs to the power jack adapter then using a multimeter connect its red cord to the output positive and the black cord to the output negative of this device. For a beginner guide on using a multimeter check the description. So with everything connected up like so we're going to provide power to our system, we're going to turn on our multimeter to measure volts, we're going to see the output as we can see coming out of our buck converter right now is 12.17 volts. So that's too many. So we're going to tone that down a little bit by adjusting the screw trim potentiometer to our desired 2.8 volts, now these LED drivers have two trim potentiometers that you can adjust with a screwdriver they rotate significantly more than anyone with experience of a normal potentiometer would realize from the smallest voltage up to the highest it can take 40 plus full rotations the same goes for the current potentiometer.

I'll now adjust the multimeter so that it can measure current note that you will need to move the multimeter red wire and adjust the setting wheel when measuring for current so we're now measuring the amperage through the system we're going to adjust it once again with our little screwdriver.

And there it is we now have a correctly calibrated buck converter for a 3 watt red LED now quickly in regards to selecting the right power supply the output voltage needs to be at least a few volts higher than the total forward voltage rating of the LEDs no matter what LED driver you choose there will be some transforming inefficiencies.

Forward voltage is the voltage in which current starts to flow in the normal conducting direction for each specific LED this can be found on the specification sheet, also quickly 18 awg that's american wire gauge is going to do perfectly for our purposes here stranded wire is preferable, it is important to get the right gauge for the application to thin a wire it will potentially get hot and heat the wire to the point where it will melt and break the circuit. From the website engineers toolbox here is the table that covers awg sizing with regards to the current through the system as you can see our 750 milliamp forward current demand is very safely met using this 18 awg wire.

With our correctly adjusted step down module let's drive a single high-power LED on screen now is the schematic of the setup we're going to do today I will only solder the sections I have no choice which are the pads on the LED nodes all other connections are screwed down terminals their twisted stranded wire is best for screw down terminals keep in mind that the 3 watt LED has been mounted to a heatsink.

First connect up the negative LED pad to the negative output on the LED driver screw it down to lock it into place then connect the positive LED pad to the positive output on the LED driver, connect the wire coming from the positive barrel jack to the positive input on the LED driver, then connect the negative barrel jack to the negative input on that LED driver, and with that complete let's get power into our system.

As soon as the power comes out of that buck converter into the LED it's gonna come up really bright don't stare directly at it your eyes are gonna thank me. So with one under our belt let's go for four we're now gonna put four of these high-power three watt red LEDs in series just like the schematics on screen now knowing that it is four LEDs in a row the current coming out of the LED driver can stay the same, however, we will need to increase the voltage a voltage of two to two point eight volts is needed for a single LED. Therefore, for four LEDs we're gonna need four times that much which results in a required voltage of 8 to 12.2 volts to make this adjustment we will need to use our multimeter again to help get that voltage trim potentiometer to where it needs to be.

The other new addition to this schematic is the added switch, with this we can then have easy control of when we want the LEDs on and when we want the LEDs off and I'm going to mount this into a 3D-printed case. So with all our components dialed in let's wire it up. First I will remove the positive connection to input so I can wire the switch in wire the toggle switch to the positive input, and the barrel side of the barrel jack. Connect the positive LED side to the positive output, then connect the negative LED side to the negative output also be sure to connect the LEDs to a heat sink. I printed an enclosure for the LED driver too, so I'm going to fit that right now, and here is everything all wired up exactly like the schematic this heatsink is overkill for these LEDs but it is convenient to show you how you can screw down the pcb onto the surface thanks to their star shapes. Just make sure not to short them via the heatsink via one of these screws this aluminum heatsink came from pulling apart a peltier thermoelectric cooler from adafruit, you could use a simple bar of aluminum from a hardware store or use four little heatsinks like before.

Proof's in the pudding and it's time for demonstration so with power to the system we can control it with our toggle switch like so avert your eyes. So not only do you have all the knowledge on part selection when it comes to these high-power LEDs but you also know exactly how to wire them up and how to harness their bright properties. Other colors are definitely available from green, blue, red, that I used here, warm white, cool white, or there are even triple output high-power rgb LEDs, which would need to be wired up slightly different but can produce all the colors.

Currently we have these lights pushing out the maximum amount of light possible if you wanted to add the ability to dim the lights this is the perfect opportunity to use a microcontroller like an arduino or an ESP32 board.

Also for this setup, I 3D-printed an enclosure for the step down module and mount for the toggle switch both of these files are freely available online linked down below if you'd like. And that's all for today we are full-time makers and here to help if you have any questions pop them down below or on our Core Electronics forum so with that until next week! Stay cozy.



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