Light Emitting Diodes (LEDs) Tutorial - SparkFun Learn

Author: Ruby

Apr. 29, 2024

Light Emitting Diodes (LEDs) Tutorial - SparkFun Learn

If you are looking for more details, kindly visit smd led chart.

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How to Use Them

So you've come to the sensible conclusion that you need to put LEDs on everything. We thought you'd come around.

Let's go over the rule book:

1) Polarity Matters

In electronics, polarity indicates whether a circuit component is symmetric or not. LEDs, being diodes, will only allow current to flow in one direction. And when there's no current-flow, there's no light. Luckily, this also means that you can't break an LED by plugging it in backwards. Rather, it just won't work.

The positive side of the LED is called the "anode" and is marked by having a longer "lead," or leg. The other, negative side of the LED is called the "cathode." Current flows from the anode to the cathode and never the opposite direction. A reversed LED can keep an entire circuit from operating properly by blocking current flow. So don't freak out if adding an LED breaks your circuit. Try flipping it around.

2) Moar Current Equals Moar Light

The brightness of an LED is directly dependent on how much current it draws. That means two things. The first being that super bright LEDs drain batteries more quickly, because the extra brightness comes from the extra power being used. The second is that you can control the brightness of an LED by controlling the amount of current through it. But, setting the mood isn't the only reason to cut back your current.

3) There is Such a Thing as Too Much Power

If you connect an LED directly to a current source it will try to dissipate as much power as it's allowed to draw, and, like the tragic heroes of olde, it will destroy itself. That's why it's important to limit the amount of current flowing across the LED.

For this, we employ resistors. Resistors limit the flow of electrons in the circuit and protect the LED from trying to draw too much current. Don't worry, it only takes a little basic math to determine the best resistor value to use. You can find out all about it in the example applications of our resistor tutorial!

Resistors

April 1, 2013

A tutorial on all things resistors. What is a resistor, how do they behave in parallel/series, decoding the resistor color codes, and resistor applications.

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Don't let all of this math scare you, it's actually pretty hard to mess things up too badly. In the next section, we'll go over how to make an LED circuit without getting your calculator.

LEDs Without Math

Before we talk about how to read a datasheet, let's hook up some LEDs. After all, this is an LED tutorial, not a reading tutorial.

It's also not a math tutorial, so we'll give you a few rules of thumb for getting LEDs up and running. As you've probably put together from the info in the last section, you'll need a battery, a resistor, and an LED. We're using a battery as our power source, because they're easy to find and they can't supply a dangerous amount of current.

The basic template for an LED circuit is pretty simple, just connect your battery, resistor and LED in series. Like this:


330 Ohm Resistor

A good resistor value for most LEDs is 330 Ohms ( orange  -  orange  -  brown ). You can use the information from the last section to help you determine the exact value you need, but this is LEDs without math... So, start by popping a 330 Ohm resistor into the above circuit and see what happens.

Trial and Error

The interesting thing about resistors is that they'll dissipate extra power as heat, so if you have a resistor that's getting warm, you probably need to go with a smaller resistance. If your resistor is too small, however, you run the risk of burning out the LED! Given that you have a handful of LEDs and resistors to play with, here's a flow chart to help you design your LED circuit by trial and error:


Throwies with a Coin Cell Battery

Another way to light up an LED is to just connect it to a coin cell battery! Since the coin cell can't source enough current to damage the LED, you can connect them directly together! Just push a CR2032 coin cell between the leads of the LED. The long leg of the LED should be touching the side of the battery marked with a "+". Now you can wrap some tape around the whole thing, add a magnet, and stick it to stuff! Yay for throwies!


Of course, if you're not getting great results with the trial and error approach, you can always get out your calculator and math it up. Don't worry, it's not hard to calculate the best resistor value for your circuit. But before you can figure out the optimal resistor value, you'll need to find the optimal current for your LED. For that we'll need to report to the datasheet...

Get the Details

Don't go plugging any strange LEDs into your circuits, that's just not healthy. Get to know them first. And how better than to read the datasheet.

As an example we'll peruse the datasheet for our Basic Red 5mm LED.

LED Current

Starting at the top and making our way down, the first thing we encounter is this charming table:

Ah, yes, but what does it all mean?

The first row in the table indicates how much current your LED will be able to handle continuously. In this case, you can give it 20mA or less, and it will shine its brightest at 20mA. The second row tells us what the maximum peak current should be for short bursts. This LED can handle short bumps to 30mA, but you don't want to sustain that current for too long. This datasheet is even helpful enough to suggest a stable current range (in the third row from the top) of 16-18mA. That's a good target number to help you make the resistor calculations we talked about.

The following few rows are of less importance for the purposes of this tutorial. The reverse voltage is a diode property that you shouldn't have to worry about in most cases. The power dissipation is the amount of power in milliWatts that the LED can use before taking damage. This should work itself out as long as you keep the LED within its suggested voltage and current ratings.

LED Voltage

Let's see what other kinds of tables they've put in here... Ah!

This is a useful little table! The first row tells us what the forward voltage drop across the LED will be. Forward voltage is a term that will come up a lot when working with LEDs. This number will help you decide how much voltage your circuit will need to supply to the LED. If you have more than one LED connected to a single power source, these numbers are really important because the forward voltage of all of the LEDs added together can't exceed the supply voltage. We'll talk about this more in-depth later in the delving deeper section of this tutorial.

LED Wavelength

The second row on this table tells us the wavelength of the light. Wavelength is basically a very precise way of explaining what color the light is. There may be some variation in this number so the table gives us a minimum and a maximum. In this case it's 620 to 625nm, which is just at the lower red end of the spectrum (620 to 750nm). Again, we'll go over wavelength in more detail in the delving deeper section.

LED Brightness

The last row (labeled "Luminous Intensity") is a measure of how bright the LED can get. The unit mcd, or millicandela, is a standard unit for measuring the intensity of a light source. This LED has an maximum intensity of 200 mcd, which means it's just bright enough to get your attention but not quite flashlight bright. At 200 mcd, this LED would make a good indicator.

Viewing Angle

Next, we've got this fan-shaped graph that represents the viewing angle of the LED. Different styles of LEDs will incorporate lenses and reflectors to either concentrate most of the light in one place or spread it as widely as possible. Some LEDs are like floodlights that pump out photons in every direction; Others are so directional that you can't tell they're on unless you're looking straight at them. To read the graph, imagine the LED is standing upright underneath it. The "spokes" on the graph represent the viewing angle. The circular lines represent the intensity by percent of maximum intensity. This LED has a pretty tight viewing angle. You can see that looking straight down at the LED is when it's at its brightest, because at 0 degrees the blue lines intersect with the outermost circle. To get the 50% viewing angle, the angle at which the light is half as intense, follow the 50% circle around the graph until it intersects the blue line, then follow the nearest spoke out to read the angle. For this LED, the 50% viewing angle is about 20 degrees.

Dimensions

Finally, the mechanical drawing. This picture contains all of the measurements you'll need to actually mount the LED in an enclosure! Notice that, like most LEDs, this one has a small flange at the bottom. That comes in handy when you want to mount it in a panel. Simply drill a hole the perfect size for the body of the LED, and the flange will keep it from falling through!

Now that you know how to decipher the datasheet, let's see what kind of fancy LEDs you might encounter in the wild...

Types of LEDs

Congratulations, you know the basics! Maybe you've even gotten your hands on a few LEDs and started lighting stuff up, that's awesome! How would you like to step up your blinky game? Let's talk about makin' it fancy outside of your standard LED.

Close Up of Super Bright 5mm LED Close Up

Types of LEDs

Here's the cast of other characters.

RGB LEDs

RGB (Red-Green-Blue) LEDs are actually three LEDs in one! But that doesn't mean it can only make three colors. Because red, green, and blue are the additive primary colors, you can control the intensity of each to create every color of the rainbow. Most RGB LEDs have four pins: one for each color, and a common pin. On some, the common pin is the anode, and on others, it's the cathode.

RGB Common Clear Cathode LED

LEDs w/ Integrated Circuits

Cycling

Some LEDs are smarter than others. Take the cycling LED, for example. Inside these LEDs, there's actually an integrated circuit that allows the LED to blink without any outside controller. Here's a closeup of the IC (the big, black square chip on the tip of the anvil) controlling the colors.

5mm Slow Cycling LED Close Up

Simply power it up and watch it go! These are great for projects where you want a little bit more action but don't have room for control circuitry. There are even RGB flashing LEDs that cycle through thousands of colors!

Addressable LEDs

Other types of LEDs can be controlled individually. There are different chipsets (WS2812, APA102, UCS1903, to name a few) used to control an individual LED that is chained together. Below is a closeup of a WS2812. The bigger square IC on the right controls the colors individually.

Addressable WS2812 PTH Close Up

Built-In Resistor

What is this magic? An LED with a built-in resistor? That's right. There are also LEDs that include a small, current limiting resistor. If you look closely at the image below, there is a small, black square IC on the post to limit the current on these types of LEDs.

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LED with Built-In Resistor Close Up

So plug the LED with built-in resistor to your power source and light it up! We have tested these types of LEDs at 3.3V, 5V, and 9V.

Super Bright Green LED with Built in Resistor Powered

Note: The datasheet for the LEDs with built-in resistor indicates that the recommended forward voltage is around 5V. Testing one out at 5V, it pulls about 18mA. Stress testing with a 9V battery, it pulls about 30mA. This is probably at the higher end of the input voltage. Using a higher voltage can reduce the life of the LED. At about 16V, the LED blew out under our stress tests.

Surface Mount (SMD) Packages

SMD LEDs aren't so much a specific kind of LED but a package type. As electronics get smaller and smaller, manufacturers have figured out how to cram more components in a smaller space. SMD (Surface Mount Device) parts are tiny versions of their standard counterparts. Here's a closeup of a WS2812B addressable LED packaged into a small 5050 package.

Addressable WS2812B Close Up

SMD LEDs come in several sizes, from fairly large to smaller than a grain of rice! Because they're so small, and have pads instead of legs, they're not as easy to work with, but if you're tight on space, they might be just what the doctor ordered.

WS2812B-5050 Package APA102-2020 Package

SMD LEDs also make it easier and quicker for pick and place machines to populate a lot of LEDs onto PCBs and strips. You would probably not to manually solder all of those components by hand.

Close Up of 8x32 Addressable (WS2812-5050) LED Matrix 5M Addressable (APA102-5050) LED Strip Powered

High Power

High-Power LEDs from manufacturers like Luxeon and CREE, are crazy bright. These are brighter than the super brights! Generally, an LED is considered High-Power if it can dissipate 1 Watt or more of power. These are the fancy LEDs that you find in really nice flashlights. Arrays of them can even be built for spotlights and automobile headlights. Because there's so much power being pumped through the LED, these often require heatsinks. A heatsink is basically a chunk of heat conducting metal with lots of surface area whose job is to transfer as much waste heat into the surrounding air as possible. There can be some heat dissipation built into the design of some breakout board such as the one shown below.

High Power RGB LED Aluminum Back for some Heat Dissipation

High-Power LEDs can generate so much waste heat that they'll damage themselves without proper cooling. Don't let the term "waste heat" fool you, though, these devices are still incredibly efficient compared to conventional bulbs. To control, you could use a constant current LED driver.

Special LEDs

There are even LEDs that emit light outside of the normal visible spectrum. You probably use infrared LEDs every day, for instance. They're used in things like TV remotes to send small pieces of information in the form of invisible light! These may look like standard LEDs so it will be hard to distinguish from normal LEDs.

IR LED

On the opposite end of the spectrum you can also get ultraviolet LEDs. Ultraviolet LEDs will make certain materials fluoresce, just like a blacklight! They're also used for disinfecting surfaces, because many bacteria are sensitive to UV radiation. They may also be used counterfeit detection (bills, credit cards, documents, etc), sun burns, the list goes on. Please wear eye protection when using these LEDs.

UV LED Inspecting a US Bill

More LEDs

With fancy LEDs like these at your disposal, there's no excuse for leaving anything un-illuminated. However, if your thirst for LED knowledge hasn't been slaked, then read on, and we'll get into the nitty-gritty on LEDs, color, and luminous intensity!

Delving Deeper

So you've graduated from LEDs 101 and you want more? Oh, don't worry, we've got more. Let's start with the science behind what makes LEDs tick... err... blink. We've already mentioned that LEDs are a special kind of diode, but let's delve a little deeper into exactly what that means:

What we call an LED is really the LED and the packaging together, but the LED itself is actually tiny! It's a chip of semiconductor material that's doped with impurities which creates a boundary for charge carriers. When current flows into the semi-conductor, it jumps from one side of this boundary to the other, releasing energy in the process. In most diodes that energy leaves as heat, but in LEDs that energy is dissipated as light!

The wavelength of light, and therefore the color, depends on the type of semiconductor material used to make the diode. That's because the energy band structure of semiconductors differs between materials, so photons are emitted with differing frequencies. Here's a table of common LED semiconductors by frequency:

Truncated table of semiconductor materials by color. The full table is available on the Wikipedia entry for "LED"

While the wavelength of the light depends on the band gap of the semiconductor, the intensity depends on the amount of power being pushed through the diode. We talked about luminous intensity a little bit in a previous section, but there's more to it than just putting a number on how bright something looks.

The unit for measuring luminous intensity is called the candela, although when you're talking about the intensity of a single LED you're usually in the millicandela range. The interesting thing about this unit is that it isn't really a measure of the amount of light energy, but an actual measure of "brightness". This is achieved by taking the power emitted in a particular direction and weighting that number by the luminosity function of the light. The human eye is more sensitive to some wavelengths of light than others, and the luminosity function is a standardized model that accounts for that sensitivity.

The luminous intesity of LEDs can range from the tens to the tens-of-thousands of millicandela. The power light on your TV is probably about 100 mcd, whereas a good flashlight might be 20,000 mcd. Looking straight into anything brighter than a few thousand millicandela can be painful; don't try it.

Forward Voltage Drop

Oh, I also promised that we'd talk about the concept of Forward Voltage Drop. Remember when we were looking at the datasheet and I mentioned that the Forward Voltage of all of your LEDs added together can't exceed your system voltage? This is because every component in your circuit has to share the voltage, and the amount of voltage that every part uses together will always equal the amount that's available. This is called Kirchhoff's Voltage Law. So if you have a 5V power supply and each of your LEDs have a forward voltage drop of 2.4V then you can't power more than two at a time.

Kirchhoff's Laws also come in handy when you want to approximate the voltage across a given part based on the Forward Voltage of other parts. For instance, in the example I just gave there's a 5V supply and 2 LEDs with a 2.4V Forward Voltage Drop each. Of course we would want to include a current limiting resistor, right? How would you find out the voltage across that resistor? It's easy:

5 (System Voltage) = 2.4 (LED 1) + 2.4 (LED 2) + Resistor

5 = 4.8 + Resistor

Resistor = 5 - 4.8

Resistor = 0.2

So there is .2V across the resistor! This is a simplified example and it isn't always this easy, but hopefully this gives you an idea of why Forward Voltage Drop is important. Using the voltage number you derive from Kirchhoff's Laws you can also do things like determine the current across a component using Ohm's Law. In short, you want your system voltage equal to the expected forward voltage of your combined circuit components.

Calculating Current Limiting Resistors

If you need to calculate the exact current limiting resistor value in series with an LED, check out one of the example applications in the resistors tutorial for more information.

Equation Used to Calculate a Current Limiting Resistor

Everything about LEDs: Basics of High Power LED Lighting

LEDs are appropriate for many lighting applications, they are designed to produce a lot of light from a small form factor while maintaining fantastic efficiency. Here at LEDSupply, there are a variety of LEDs for all kinds of different lighting applications, the trick is knowing how to use them. LED technology is a tad different than other lighting that most people are familiar with. This post is here to explain everything you need to know about LED lighting: how to power LEDs safely so you get the most light and the longest lifetime possible.

What Exactly is an LED?

An LED is a type of diode that turns electrical energy into light. For those that don’t know, a diode is an electrical component that only works in one direction. Basically, an LED is an electrical component that emits light when electricity flows through in one direction, from the Anode (positive side) to the Cathode (negative side). LED is an acronym standing for ‘Light Emitting Diode’. Basically, LEDs are like tiny light bulbs, they just require a lot less power to light up and are much more efficient in producing high light outputs.

LED Types

In general terms, we carry two different types of LEDs:

5mm Through-Hole & Surface Mount.

5mm LEDs

5mm LEDs are diodes inside a 5mm diameter lens with two thin metal legs on the bottom. They are used in applications where a lower amount of light is required. 5mm LEDs also run at much lower drive currents, maxing out at around 30mA, whereas Surface Mount LEDs require a minimum of 350mA. All our 5mm LEDs are from top manufacturers and are available in a variety of colors, intensities, and illumination patterns. Through-hole LEDs are great for small flashlight applications, signage, and anything where you are using a breadboard as they can be used easily with their leads. Check out our guide to setting up 5mm LEDs for more info on these tiny light sources.

Surface Mount LEDs (SMD)

Figure 1 – Bare Emitter

Surface Mount LEDs are diode(s) that can be placed on a substrate (circuit board) with a silicon dome over the diode to protect it (see Fig. 1). We carry high-power Surface Mount LEDs from industry leaders Cree and Luxeon. Both are excellent in our opinion, that is why we carry them after all. Some prefer one over the other but that comes with experience and knowing what to look for. Cree tends to have higher listed Lumen outputs and is a market leader in the High-Power LED sector. Luxeon, on the other hand, has excellent colors and thermal control.

High Power LEDs come as bare emitters (as seen in Fig. 1) or are mounted to a Metal Core Printed Circuit Board (MCPCB). The boards are insulated and contain conductive tracks for easy circuit connections. Our 20mm 1-Up and 3-Up starboard designs are the best sellers. We also offer QuadPod’s which can hold 4 high-power LEDs on a board slightly larger than the 20mm stars (see Fig. 2). All our high-power LED options can be built on a linear design as well. The LuxStrip can house 6 LEDs per foot and is easily connected up to 10 feet long.

Figure 2 – MCPCB Options

Polarity Matters: Wiring LEDs

Electronic polarity indicates whether a circuit is symmetric or not. LEDs are diodes, therefore only allowing current to flow in one direction. When there is no current flow, there will be no light. Thankfully this means that if we wire an LED in backward, it will not burn the whole system up, it just won’t come on.

The positive side of the LED is the Anode and the negative side is the Cathode. Current flows from the anode to the cathode and never in the other direction, so it is important to know how to tell the anode and cathode apart. For surface mount LEDs this is easy as the connections are labeled, but for 5mm LEDs ook for the longer lead which is the anode (positive), take a look at Figure 3 below.

Figure 3 – Finding the anode and cathode of an LED

Color Options

One of the great things about LEDs is the different options and kinds of light you can get from them.

White LEDs

Correlated Color Temperature (CCT) is the process of creating different white light at different temperatures. Color temperature is specified in degrees Kelvin (K), which is a temperature scale in which zero occurs at absolute zero and each degree equals one Kelvin. The lower temperatures from 3,000K to 4,500K tend to be warmer to neutral white. The higher temps 5,000K+ are the cool whites, also known as ‘daylight white’.

Color LEDs

For colors, what really matters is the wavelength in nanometers (nm). For certain applications, colors are needed for the visual effect, but sometimes certain wavelengths are needed for applications like curing, growing, reef tank lighting, and much more. See Fig. 4 for an idea of what wavelengths and temperatures produce certain colors.

Figure 4 – LED colors and color temperature

We try to carry similar color temperatures and wavelengths for each brand and type of LED. You can always find the color or wavelength of our LEDs on the sub-section of the product page and can even search by color from our LEDs dropdown menu on the homepage. In white, we carry 3000K, 4000K, 5000K, and 6500K. As far as colors go, we carry from 400-660nm.

LED Brightness

LEDs are not only known for their colors, they are also a lot brighter than other light sources. Sometimes it is hard to tell how bright an LED will be because it is measured in Lumens. A Lumen is a scientific unit measuring luminous flux or the total amount of visible light from a source. Note that 5mm LEDs are usually listed in millicandelas (mcd). For 5mm LEDs, their viewing angle also affects the light output they give off, for more on that see here.

Why drive current matters…

The amount of light (Lumens) an LED emits depends on how much current is supplied. Current is measured in milliamps (mA) or amps (A). High-power LEDs can take currents from 350mA to 3000mA. LEDs vary on their current ratings so be sure to keep track of this when picking an LED and driver.

Determining the Brightness

Now comes the tricky part, selecting the LED and driver combination that will output the light needed. We have done a lot of the groundwork here, in a post measuring the brightness of each high-power LED at different drive currents. Take note that these are measures for 1-Up stars so if you want more light the 3-Up LEDs are a good option as they are triple the light within the same footprint.

The above resource can always be used for determining the light output from an LED, but finding it manually is not very hard.

To do so, information is needed from the datasheet of the LED. On all of our LED pages, we link to the manufacturer’s datasheet at the bottom of the page.

Example: Finding brightness of Cree XP-L at 2100mA

In this example, we are using the Cree XP-L. First, find the Flux Characteristics table (figure 5). We will touch on binning later which is labeled in the ‘Group’ column, but let us assume we are going to use a cool white XP-L from the highest bin (v5). The highlighted number is the typical flux @ 1050mA which is the current the XP-L is measured at. To the right of that are the typical Lumen numbers for 1500, 2000, and 3000mA drive currents.

Figure 5 – LED Luminous Flux Chart

For the sake of this example, say we want to run this LED with a 2100mA BuckBlock LED driver and we need to find what the light output would be like. When driving an in-between drive current that is not listed, find the relative flux vs. current graph on the datasheet that looks like the graph to the right.

The arrow is the tested (base) output (at 100% relative flux). Following the curve to 2100mA (?) we see that this is a 75% increase in light. Taking the 460 lumens from above and multiplying it by 1.75 we can see that the cool white XP-L running at 2100mA gives off about 805 Lumens.

It may be hard to find the LED and Lumen output needed when switching to LEDs. This is due to the fact that light was always measured by the wattage of a bulb. LEDs have much better efficacy which makes it nearly impossible to measure in this way anymore as a 50 Watt LED will be significantly brighter than a 50 Watt Incandescent. In Figure 7 we show different incandescent bulbs and how many Lumens they give output. This helps give a better idea of the light to expect from an LED and if it will be as much as the old lighting.

Figure 6 – Incandescent Wattage to Lumens

Viewing Angle and Optics

Our 5mm LEDs have listed viewing angles for each so just search for one that will work for you. As far as our surface mount LEDs go, most of them give off a very wide angle at 125 degrees! Luckily, the LED starboards are compatible and easy to use with LED optics. These secondary optics are used to focus the light, they can reflect the light from an LED into spot, medium spot, wide spot, or elliptical and oval patterns.

As seen in Figure 8, 1-Up optics are cone-shaped and require an optic holder. In the case of our LED boards, optic holders have four legs that sit down into the grooves of the star. Triple LED stars are also compatible with Carclo optics, built with three holes in the board for the legs of the optic to fit in.

Figure 7 – LED optics and holders

How to Power LEDs

LEDs are known for having the best efficacy out of all other light sources. Efficacy is the measure of how well a light source produces visible light, also described as Lumens per Watt. In other words, how much light are we getting for our watt of power? To find this, first, find out the wattage of the LED in use. In order to find watts, you need to multiply Forward Voltage (the voltage at which current starts to flow in the normal conducting direction) by drive current in Amps (note that it NEEDS to be in amps…not milliamps). Let’s take a look at the Cree XP-L 1-up LED as an example.

Figure 8 – Forward Voltage of an LED

Say we are running this Cree XP-L at 2000mA. From Figure 8 you can see that at this drive current the forward voltage is 3.15. So to find watts we multiply 3.15 (forward voltage) by 2 A (2000mA = 2 Amps) which comes out to be 6.3 Watts.

So now to find Efficacy, we just need to divide 742 Lumens (the tested amount of Lumens for this LED at 2000mA) by 6.3 Watts. So the Efficacy (Lumens/watt) of this Cree XP-L is 117.8. This is great efficacy but also note Cree boasts that the XLamp XP-L LED has breakthrough efficacy of 200 lumens/watt running at 350mA. It is good to know that the efficacy goes down as you run more current to the LED as this increases heat which does make the LED a bit less efficient. Sometimes you will need to accept this if you need the LED to be very bright, but if you are wanting to get the best efficacy then you should run LEDs at a lower current. This is all helpful in determining how much power your applications will need as well as figuring out energy savings down the road.

A little bit more on LED drivers

This means that you need to find an LED driver that has the capability of driving LEDs at the current you need in order to get the amount of Lumens you’d like. An LED Driver is an electrical device that regulates the power to an LED or string(s) of LEDs. The driver responds to the changing needs of the LED by supplying a constant amount of power to the LED as its electrical properties change with the temperature. A good analogy in understanding this is that of a car on cruise control. As the car (LED) goes through hills and valleys (temperature changes), the cruise control (driver) makes sure it stays at a steady speed (light), regulating the gas (power) needed in doing so. The driver is so important because LEDs require very specific electrical power in order to operate properly. If the voltage supplied to the LED is lower than required, very little current runs through the junction, resulting in low light and poor performance. On the other hand, if the voltage is too great, too much current flows to the LED and it can overheat and be severely damaged or fail completely (thermal runaway). Always make sure you check the LEDs datasheet so you know what current is recommended to avoid these issues.

How much voltage do I need to light up an LED?

This is a common question asked and is actually pretty easy to figure out. All you need to know is your LED(s) forward voltage. If you have multiple LEDs in series then you need to take into account all the forward voltages combined, if you have a parallel circuit then you only need to take into account the forward voltage of how many LEDs you have per string. For more on wiring setups, see here. It is a good idea to keep at least a 2 volt overhead as some drivers (like the LuxDrive drivers) require this for the driver to work properly. So if your total forward voltage for a series circuit is 9.55, you should be safe with a 12V supply. For off-line drivers (AC input) just know the output voltage they are rated at and make sure you are covered, so an AC input driver with an output range of 3-12VDC would work for this application as well.

Heat Control

Finding the wattage of your system also helps you know more about the heat control you will need. Since these LEDs are high-power, they do create heat which can be very bad as you can learn here. Too much heat will make the LEDs produce less light as well as cut down on the lifetime. We always recommend using a heatsink and like to say to use about 3 square inches for every watt of LEDs. For larger wattages, I would recommend looking for a heatsink that is recommended for the number of watts you are running.

LED Binning & Quality

With the LED industry growing at a pretty rapid pace right now, it is important to understand the difference in LEDs out there. This is a common question as LEDs can range from very cheap to very expensive. I’d be careful in buying cheap LEDs as you always get what you pay for, yes the LEDs might work great at first but they usually tend not to last as long or will burn out fast because of poor testing.

All the LEDs carried here at LEDSupply are carefully selected. We only stock the best brands and color temperatures. Our vast experience in the industry has helped us learn the importance of quality manufacturing and binning of LEDs as well. In the manufacturing of LEDs, there is a variation of performance around average values in the technical datasheets. For this reason, manufacturers bin the LEDs for luminous flux, color, and forward voltage. We select the bins with the highest luminous flux (visible light) and lowest forward voltage, as this makes sure we have the LEDs with the best efficacy. A large amount of LED products are cheaply made and not documented correctly, which leads to many failed projects and then makes people think LEDs actually don’t last as long as they are said to. With our experience and buying power, we are able to offer the best products at reasonable prices.

This should give you a good start to understanding LEDs and what to look for, but if you have more questions or would like more info on a certain product and whether it would work for you, we are here to help. Just email us at sales@LEDSupply.com or call us at (802) 728-6031 to chat with our very knowledgeable Tech Support Team.

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