How to Drive High Power LEDs With A DC-DC Adjustable Step-Down Module

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.

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In this video I will power a single 3W Led and then 4 of these LED nodes in series. We will figure out and select the right gauge of wire, manage heat dissipation and the power requirements using the Datasheets. This way we can select the correct electrical componentry. LEDs are incredible pieces of modern technology, the real unsung heroes in our electronics world, but they do need to be utilised correctly to take advantage of not only their incredible brightness but their long lifespan as well.

LEDs are unlike other traditional incandescent lights where higher voltages produce brighter light. The amount of light (Lumens) an LED emits depends on how much current is supplied. High-power LEDs can commonly take currents from 350mA to 3000mA. Too much current will result in thermal runaway and broken LEDs. Now most power supplies are made to regulate voltage, not current. If you connected a standard DC voltage regulated power supply to a line of LEDs it would provide too much current to the LEDs and cause them to break. Just remember that LEDs are greedy for current and need somebody to supervise them otherwise they will become gluttons and die a very early life. This is why we need a Constant Current LED Driver between the DC power supply and the LEDs. This acts as the supervisor. The LED driver can regulate the current and voltage provided to the LEDs so that they are always at the perfect level.

A buck-boost converter is a type of DC-to-DC converter that has an output voltage magnitude that is either greater than or less than the input voltage. The technology of buck, boost, and buck-boost (Step Down or Step Up) converters are utilized around the world to provide regulated low-voltage DC/DC power in nearly every electronics market. Importantly these devices manage and prevent excess current flow. If the voltage and current from the chosen power supply are too high for the LEDs you will need a buck (step-down) converter. If voltage and current from the power supply are too low for the LEDs you will need a boost (step-up) converter.

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0:00 Intro
0:43 Powering LED Overview
1:07 Video Details
1:48 What You Need
2:40 More Current = More Lumens (Up to a point)
3:02 Why a LED Driver?
3:36 Adjusting the LED Driver Output
5:37 Choosing Power Supply
6:04 Choosing Wire Gauge
6:40 One 3W LED System Setup
7:42 First Pay-off!
7:56 Four 3W LED System Setup
10:04 Second Pay-off!
10:17 Where to Now
11:06 Outro

[PeterAMann-jffx]

One of the finest educators in electronics I have known; well planned and delivered. Kudos :)

[ettilapse]

Man, every time I need some tips on my tech experiments, I find you every time. Appreciate you and your work man. Thank you.

[khalid_works]

Simple, Informative & Clear. Thank you a lot for make this video. You make connect high power led easy for me specially I want to avoid cheap led drivers and resistors.

[teammouse]

You deserve a lot more likes! Best explanation yet, thank you!

[vladimirjosifovski]

At the end of your presentation, you mentioned that we can use microcontroller to dim those high power leds. Do you have any project describing details how to connect microcontroller to DC-DC controller ? (not led stripes, I need to dim high power leds)

[ElLenadorLA]

You may have just solved a problem that’s been wracking my brain! Thank you!

[Prasanna_Naik]

This is really amazing. I really feel this channel videos are highly underrated. You deserve more likes, views and comments brother. Also please make a video on Waveshare Sim 7600G-H use with RaspberryPi running Openwrt. I have commented the same on your Sim7600G-H video.

[patmat.]

So it's not just a current limitator, even when 'short-circuited' by your multimeter in current mode the driver has a constant output... which means there must be an automatic rheostat inside (?)

[joshuamittie]

I'm wondering I bought led headlights they say input voltage is 12 to 36 volts and thought I could buy a couple boost converter and turn up voltage for brighter lights for offroad and track night use . Not sure how it works exactly. No problem soldering and I could pot them in epoxy to waterproof. So if anyone can give advice perhaps a link to what I'm looking for . Thank you for the video

[austingodbey]

Could you add a PWM dimmer into this to achieve dimming? If so would that go before or after the step down module? Thank you, great video!

[bravofoxtrot]

Great video and channel. What if you have 4 LED's run in series and then 4 groups of 4 LED's run in parallel. The voltage would be set at 8 to 12.2 V on the Buck but what would the Current be set at? Each LED needs 750 mA but in parallel they need 3A. How would you trim the current? Would that cause the thermal runaway we are trying to avoid? Thanks

[Shenzhenottimatechnologycoltd]

You are welcome to test our LED driver products

[ianadams]

Very helpful, thanks for walking us through this! I looked everywhere trying to figure out how to light some cob leds I recently got, but your step by step video explained it very well. I was wondering though, I'm trying to build an infrared illuminator from some 3 watt 850nm cobs I got, but the listing didn't mention what voltage they are, only that they recommended 600 milliamps for the current. How do I figure out the voltage requirement? I read you can use the diode mode on a multimeter to read the voltage on a led, but it didn't seem to work on mine.

[ddistrbd]

good video, I wish you also showed 5 led beads connected in parallel.

[kbssaprodussoes]

Why when we wire two 12v 30w white leds in series, the power supply is regulated to 24v and 3 amps, why does the voltage across the leds drops to 18w while running? should we match the voltage to specs or they are already at their max capacity?

[caloigarcia]

vEry well explainEd sir..thAnk fOr thE knOwledge

[Hobypyrocom]

great video, but how to connect the microcontroller with the step down buck converter? should you use mosfets? how to wire them in practical environment, where leds will need long power cables, should you add the converter on the powering side or the led side of the cables? how to calculate and compensate for the resistance and losses of long powering cables for the led's?

[arthurpillart]

For school project i need to power 6m of RGB LEDSTRIP 60watt and 24v what type of led drive should i use and how do i connect it to my arduino?

[robertroe]

Great video but some questions. The buck converter is pre-set to 750ma by directly shorting the meter across the output. It would be interesting to see what the actual current draw is, both with one and five LED's.

[abrahamjerry]

Can a 5v output from a power bank be used instead of the 12v shown in this video to drive the same LED?