What Is an LED Driver, and Why Do I Need One?

LED drivers tend to be the most confusing component of light-emitting diode technology. Since there are numerous variations to consider, the entire experience can feel a little overwhelming. If you desire to replace an existing light bulb with an LED alternative, your goal is to take one product out and put another one in to use.


This guide provides the essential factors to review when choosing an LED driver for your upcoming application. It also delivers the information behind those data points to ensure the right decision gets made the first time around.


Why Do You Need an LED Driver?


The publicized benefits of LED technology are familiar to most people today. Because of increasing energy regulations and the practical benefits these bulbs provide, this lighting option makes sense for many homes and businesses.


Many people don't realize that LED lights use a specialized driver to operate. This power supply is similar to a ballast for a fluorescent lamp, or the transformers used for low-voltage products. It delivers the correct power supply that lets the LED function as expected.


Without an appropriate driver, the LED light bulbs could not perform at their best.


Every LED light bulb or source requires a driver to function. Most use an integrated driver within the bulb, especially if they're meant for household use. If the product is rated to run with a 120V power source, it probably includes this need so that a plug-and-play experience is available.


A separate driver is often needed when you need a low-voltage LED light source, like tape lights or outdoor-rated products. This power source serves two specific purposes.


  • Drivers protect LEDs from current and voltage fluctuations. When a voltage change occurs to the supply, the light output can change. When there's too much or not enough current, the output degrades faster due to the higher temperatures developing within the product.
  • LEDs run on low voltage with direct current electricity. Most fixtures are connected to a higher voltage that uses alternating current. The driver rectifies this situation without consumers needing to create buffers or bridges when they purchase the product.


What Type of External LED Driver Do I Need?


Two types of external LED drivers are available today. You can pick up a constant-voltage or a constant-current option.


A third style, which is an alternating-current LED driver, is also usable in specific situations. When you're replacing the driver for your LED stack, the previous input and output requirements must be closely matched to ensure operations proceed as expected.


If you don't have enough voltage for your LED driver, a boost driver can output a higher voltage than what gets supplied to the unit. That makes it possible to power more diodes in-series than with a single driver. That's especially helpful in places where your input voltage has limitations.


Here is a closer look at the differences to expect when looking at your LED driver options.


Constant-Current LED Drivers

This LED driver powers diodes that need a fixed output current and a range of output voltage. Only one current is specified when using this unit, labeled in milliamps or amps, along with a range that varies on the LED wattage.


You would use constant-current LED drivers for the following needs.


  • LED Downlights.
  • Residential and Commercial LED lighting.
  • Mood Lighting.
  • Retail Lighting.
  • LED Signs and Entertainment Lighting


Constant-Voltage LED Drivers

With this driver, an LED that requires a fixed output voltage with a max output current gets the power it needs. In these diodes, the current already receives regulation. It can be through an internal constant-current driver or a simple resistor, but it already exists. That's why it only needs one stable voltage.


  • LED Strips and Light Engines.
  • LEDs Connected in Parallel.
  • Street or Stage Lighting.
  • Architectural Lighting.
  • Moving Signs.
  • Outdoor LED Lighting Needs.


AC LED Drivers

This driver option is a no-minimum transformer. That means you could technically use it to power an incandescent or halogen bulb.


LEDs cannot operate using a conventional transformer because they're not made to detect the lower wattage levels that diodes produce.


Most AC LED drivers are used with light bulbs that already have internal drivers to create an intended result. It steps down the voltage to meet the expected requirements. Those looking at this option must read the product's datasheet – you cannot use this driver when a bulb requires a DC voltage input.


What Are the Factors to Consider?


When looking for an appropriate LED driver for your lighting needs, several factors to review can help you choose the correct product for your current and future needs.


Here is a closer look at what needs to be reviewed before choosing the most appropriate driver for your situation.


Factor to ConsiderWhy That Factor Is Important with LED Drivers
Output VoltageThis value is given in volts. If you have a constant-voltage driver, it's the same output as the LED's requirements. When you're running a string or stack, the combined voltage requirement must match what gets provided.
Output PowerThe value for this factor is in watts. It should have at least the same value as the LED used. Drivers should have a higher output power than the diodes for extra safety. When they match, that means it is running at full power, which can cause the driver to have a prematurely shortened lifespan.
Life ExpectancyLED drivers come with a life expectancy rating of several thousands of hours. It's called the mean time before failure (MTBF). Compare the level you're running to work out an appropriate time for your installation needs. Bulbs often have this information expressed as a lifetime rating on the package.
IP RatingHow much resistance to dust and moisture are needed with your LED driver? If it's going to be somewhere that these elements could be problematic, the required minimum rating is IP65. When you need a water-tight solution, an IP68 rating is better. Anything that starts with a 6 is dust-tight, while submersion protection is indicated by the second number, either 7 or 8.
Output CurrentThis measurement is typically in milliamps, but it can also be expressed in amps. You can find constant or variable drivers available to use. Your LEDs must fall within the chosen values to ensure it works correctly. You can run diodes at a lower current to extend their life expectancy.
Termination MethodHow is the LED driver connected to the application? Some designs come with wires attached, while others require a separate purchase. It might be necessary to mount the cables to it to keep a streamlined design.
EncapsulationDoes the LED driver you need require an enclosure? Is it getting built into the system? If you opt for an open-frame design, it'll be more compact so that it works with your application better. It also protects stand-alone units and IP ratings.


Class I and Class II drivers are available to use with UL certification. The latter option complies with the UL1310 standard. That means there's no risk of electric shock or fire. They can operate with less than 60v in dry applications, 30v in wet ones, and at less than five amps and 100 watts.


Class I drivers require safety protection from handling, but they're more efficient because they handle a higher number of LED lights.


How Many LEDs Can One Driver Run?


Every LED light source requires a driver. That doesn't mean you need to have a separate driver for every LED on a circuit.


The number of LEDs that one driver can run depends on the amps on the circuit and the wattage output of each bulb.


If you have a 15-amp circuit operating on a standard 120V system, it could support up to 360 lights that operate at 5 watts.


Once you have that number determined for the circuit, you can figure out the power requirements for the LEDs. That number depends on the ratings on the product itself. If the driver is strong enough, it could power all 360 LEDs in the above example.


It's also entirely possible that you'd need to use 360 drivers because each one only supports the needs of an individual diode.


If My LEDs Stop Working, Does That Mean My Driver Failed?

It is rare for a high-quality LED driver to fail because of manufacturing faults. The problem usually involves environmental factors or installation issues.


If you find LED failures happening with your stack or string, the first step to review is if a short on the output occurred. There could be connections somewhere in the lights that shorted out, causing the power supply to stop functioning as expected.


Disconnect the power supply from the LED light string or stack. Measure the voltage that comes from the supply. If you don't see any problems there, you'll know the issue is within the string and not the driver.


That's also the time to verify that you don't have too many LEDs installed on the output.


Using a higher power LED driver with enough current might be necessary to manage a startup load. You can look at the datasheets for your products to determine what is required in these circumstances.


Do LED Bulbs Have a Driver to Use?


When you install an LED light bulb at home or in the office, you're using a product that already contains a driver. That's why you can screw the product into a standard fixture to have it start working right away.


Commercial LED lights sometimes need an external driver. Warehouse, street, and area lighting are the most common examples of this requirement. The good news is that it's often cheaper to replace the driver than it is to update the entire fixture when it stops working.


It should come as no surprise that external drivers fail. If you can keep the temperature low around the fixture, you'll get to prolong the lifespan of each unit. Higher temps happen when the electrolytic capacitors begin overheating, evaporating the gel they contain.


If the gel evaporates faster than expected, the driver can stop working. You'll see the hottest point on the label, called the TC point, to see what the operating specs are for the product.



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