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Posted by Doug Root on 30th May 2020

LED Lighting and LED Drivers: A Crash Course

Here at Atlanta Light Bulbs, we take lighting very seriously. It’s our life’s work, and we have years and years of experience providing lighting of all types, including specialty lighting, to our customers for varied venues.

With that said, it can be all too easy to lose sight of how important lighting is as you go about your normal, busy day. No one really stops to think about the fact that half of what they do in the course of an average day would be difficult if not impossible without modern lighting.

Before the invention of electric lighting over 100 years ago, people had little choice but to conclude their duties with the setting of the sun or waste morning burning candles. Today, our productivity is enabled to continue round the clock, as advances in technology continue to bring affordable, effective lighting to businesses and the masses.

Many lighting solutions make use of only a few different precepts for delivering energy in the form of usable light. For example, incandescent bulbs, which have been the standard in residential lighting for many years, use the electric resistance of a filament, regulated by gas within the bulb, to produce light. In essence, current runs through the filament, heating it up until it glows. The lack of oxygen within the bulb gives it a longer lifespan than would be possible in the presence of atmospheric oxygen.

By slight contrast, other bulbs make use of fluorescence, which, to put it simply, utilize UV radiation to stimulate fluorine bearing phosphor powders into glowing. Fluorine is a highly reactive element that will glow with a visible light of a shorter wavelength when it is irradiated by ultraviolet light, which is of a different wavelength - shorter, pursuant to the laws of physics.

There are other prevalent forms of lighting besides these, and these two are only used to illustrate a few of the ways that electricity can be harnessed to produce light through processes like resistance and fluorescence. There are others, and most of them rely on the stimulation and regulation of gases and vapors to produce visible light.

By a much sharper contrast are LED lights, or light-emitting diodes, which, though they use electric current to produce light, do so in an altogether different capacity than the methods described above. Originally, LEDs were cost-prohibitive to produce because their construction necessitates the use of different types of semiconductor materials. Until relatively recently, it was extremely expensive to produce or source semiconductor materials, but about 10 years ago, their prices dropped precipitously. That has thrust LEDs into the forefront of many different lighting applications.

LEDs are vastly different from other forms of lighting and come with their own advantages because of their operation and construction. To understand these, you must first have a more thorough understanding of their operation, into which we will dive more closely.

How Does a Light Emitting Diode Work?
As we stated before, other lamps produce lighting through heated filaments or by exciting gases until they glow with visible light. LEDs are different because, in this sense, they are not truly a bulb. The bulbs of other lamps contain the gases that are necessary to regulate incandescence or to allow for luminescence. LEDs have no such gas-filled bulb. They are known as solid-state because the solid materials from which they are made actually produce the visible light. There are no filaments, no gases, and no true bulb.

Light-emitting diodes contain semiconductors that are the key to their luminescence. Simply put a semiconductor is a material that can conduct an electrical current. Typically LEDs have a semiconductor with a p-n or positive-negative junction. The positive side of the semiconductor has a positive charge and therefore an electron-hole, as the atoms on that side are lacking in electrons. The n side, or negative side, has a surplus of electrons. Diodes are fed by an anode wire and a cathode wire, and as electricity flows from the negative side to the positive side, they fill the electron holes and they release energy in the form of photons, which we see as light. This phenomenon is known as electroluminescence, or more broadly, a process by which light is directly produced through electricity.

Light-emitting diodes, therefore, do not have a bulb but a lens or a cover that helps to protect the semiconductor and to direct the light produced, which is something else to note. When LEDs were originally produced, they were not particularly adept at directional lighting. Modern advances in technology have produced ‘LED bulbs’ or sorts that take the form of many LEDs wired together to provide the multi-directional lighting and softer light that many people find necessary for their dwellings.

All of this being out of the way, because of some of the key differences between light-emitting diodes and other forms of lighting, they require specialized devices called LED drivers for their operation, and for a few different reasons at that.

What Are LED Drivers?
LED Drivers are specialized devices that make it possible for LEDs to function as they do. Without drivers, it would be effectively impossible to operate LEDs, and moreover, if you could, the lighting would be inconsistent.

In short, LEDs have very specific needs in power supply in order to operate as they are intended, which is also the reason that LED drivers are also known as LED power supplies. They are similar to the ballast that is required for the operation of fluorescent lights. Somewhat similar to a fluorescent light’s ballast, LED drivers help to provide the proper current or voltage to ensure that the LED functions as it should.

There are two main things that LED drivers specifically perform for their associated lighting circuits. LEDs are designed to run on low voltage power supplies, which is part of the reason that they are as fantastically energy efficient as they are. They do not require as much power to provide as much lighting power as they do, but they do require these devices, known as drivers, to supply them with the proper constant voltage and current.

Most places supply much higher voltage than is necessary for the operation of LED lights, and drivers alter this voltage to bring it down to the proper range. Another thing to note is that most devices run on alternating current, whereas LEDs run on the much less common direct current. LED drivers alternating current to direct current to power the LED. In that manner, they are somewhat similar in function to transformers that bring the voltage down to a fitting level for most devices to operate. They are not the same, but the function is there.

LED drivers, by the same token, also protect LEDs from alterations or surges in voltage or current that could be detrimental to their operation. LED light output is related to the supply of current on which the LED is rated to run, and changes in this can result in poor performance. LEDs do not burn out in the same way that traditional bulbs do, but undue changes in voltage or current can cause them to run hotter than usual or dimmer than usual. In the case of an LED that is running too hot, the LED can experience a degradation of light quality or output before its time, and in the case of a dimmer light the outcome is obvious - it will not provide adequate lighting.

Basically, LED drivers regulate the current and voltage supplied to LED lights so that they perform as they are supposed to perform. All LED lights require a driver for practical operation, and drivers come either as integral to the unit, in which case they are known as internal drivers, or external to it, in which case they are referred to as external drivers.

Internal Drivers
In the same way that some fluorescent lights contain ballasts that are integral to their design and necessary to their function, some LEDs contain internal drivers that are a part of the ‘bulb’ or unit so that they can be easily set up and used. Most frequently, the LEDs used in residential settings where the bulbs can simply be plugged or screwed in can come with internal drivers. That makes it easy for homeowners simply to buy the unit that is effectively ready to use. However, many other forms of LEDs use external drivers, and for a few very good reasons.

External Drivers
LED drivers are considered external when they come as a separate unit to be used in conjunction with LED lights but are not contained within the ‘bulb’ or unit itself. There are a number of reasons some lights use external drivers. Whereas internal drivers in some cases are much more convenient, external drivers are much easier to service, replace or alter to enhance the performance of LED lights.

For example, one reason that many LED lights come with external drivers is the fact that the usable lifespan of an LED can often be extended by replacing a driver. As we mentioned, LEDs do not burn out as traditional bulbs do, but instead, slowly experience a gradually diminishing of their luminosity. Though this will occur naturally over time, often the culprit to the untimely demise of an LED is the driver, which, if it is external, can be replaced to revive the LED itself.

Without overburdening you with details, one of the main reasons that LEDs experience diminished performance before they are expected to is due to overheating. Drivers sometimes help to regulate temperature and thus, if an LED is not working as it should, replacing the external driver might be able to bring some life back to it.

Types of Drivers
There are two main types of drivers, each of which is designed to service LEDs with differing needs in power. They are constant current drivers and constant voltage drivers, respectively.

Constant current LED drivers do exactly what their name suggests, which is to provide a constant current (albeit potentially at different voltages) to an LED that is specified to run off of a prescriptive range of current.

By contrast, constant voltage drivers provide a fixed output voltage to LEDs whose current is regulated either by resistors or by an internal driver of some sort. These types of drivers are designed for use with LEDs that require a fixed voltage, as the name would imply.

Other ConsiderationsTwo of the other things to take into account when investigating LED drivers are the fact that drivers can impact your ability to operate dimmable LEDs as well as to impact the color sequencing of the lights.

With regard to dimming, some drivers can affect the performance of an LED to provide the ability to dim it. This can be achieved by lowering the current going through it and thus supplying it with less power, as well as through a process known as pulse width modulation, also known as PWM.

With respect to color sequencing, it is important to understand that many ‘white’ LEDs actually give off white light through a combination of other colors (such as red, blue, and green) that when shone together, appear white. Some drivers can be used to allow only certain colors of light to be emitted through these LEDs so that you can create a full rainbow (or some subset of colors) with the same LED and the right driver.

We here at Atlanta Light Bulbs are your source not only for LED lighting solutions but also for the drivers that make their use practical. We understand that this is a lot of information to take in at once, and we welcome you to call us for more information or to clear up any questions you might have. If you know what you’re looking for, by all means, go ahead and find it on our site, but if you’d like some more information, you can reach us at 888-988-2852. We look forward to hearing from you and would love to shed some ‘light’ on LEDs and drivers.