Do I Need an LED Driver?

May 09, 14 Do I Need an LED Driver?

Due to increasing energy regulations, most people are familiar by now with the long life spans and energy savings associated with LEDs, or light-emitting diodes. However, many are not aware that these innovative light sources use specialized devices called LED drivers to operate. LED drivers (also known as LED power supplies) are similar to ballasts for fluorescent lamps or transformers for low-voltage bulbs: they provide LEDs with the correct power supply to function and perform at their best. Below, we discuss when you need an LED driver,  why you need an LED driver, and what type of driver you may need.

When Do I Need an LED Driver?

Always. Every LED light source requires a driver. The question should be whether or not you need to purchase one separately, as some LEDs already include an integrated driver within the bulb. LEDs designed for household use (bulbs with E26 / E27 or GU24 / GU10 bases and that run on 120V) typically already include a driver. However, low voltage LED light sources, such as some MR- bulbs (MR GU5.3s, MR8s, and MR11s) and tape light, as well as certain fixtures, panels, or outdoor-rated lights, usually require a separate driver. Always check your product data sheet to see if your LED light source requires a separate driver.

Why Do I Need an LED Driver?

  • LEDs are designed to run on low voltage (12-24V), direct current electricity. However, most places supply higher voltage (120-277V), alternating current electricity. An LED driver’s main purpose is to rectify higher voltage, alternating current to low voltage, direct current.
  • LED drivers also protect LEDs from voltage or current fluctuations. A change in voltage could cause a change in the current being supplied to the LEDs. LED light output is proportional to its current supply, and LEDs are rated to operate within a certain current range (measured in amps). Too much or too little current can therefore cause light output to vary or degrade faster due to higher temperatures within the LED.

In sum, LED drivers serve two purposes: to convert higher voltage, alternating current to low voltage, direct current, and to keep the voltage or current flowing through the circuit at its rated level.

What Type of LED Driver Do I Need?

There are two main types of LED drivers, constant-current and constant-voltage. Often, you can simply check the datasheet of an LED light source to find out if it requires a constant-current or constant-voltage driver. For example, if an LED datasheet says that your light source requires a 350mA output, you need a constant-current driver. If a datasheet says that your LED requires a 12-volt output, you need a constant-voltage driver. Below, we’ll review the differences between each technology.


FLX-3528WW1203Since LEDs are forward-current driven light sources, all LEDs require a constant-current driver to work. They only require one separately if they do not already include an integrated one inside the bulb. Constant-current LED drivers are available with a variety of different attributes depending on application and required electrical output. Constant-current drivers keep the current flowing through each LED at the rated current to maximize the light output and life span of each diode.  Constant-current LEDs and drivers are more widely used, as well as more efficient, than constant-voltage technologies. Examples of constant-current LEDs include tape light, signage/channel letters, under-cabinet fixtures, and pathway lighting.

Keep in mind that when constant-current LEDs are connected in a series, the voltage supply will drop with each new diode. Be sure to choose a driver with a suitable voltage to meet the current requirements. For example, if you put 15 LEDs in a series, and each LED has a voltage drop of 3 volts (at its nominal current), you will need to provide a voltage source of 45 volts (15 x 3V = 45V).


trafficinfosignIf your LEDs already include a constant-current driver as part of the assembly, an external constant-voltage driver is required.  Low-cost LED circuits that control the current flowing through the LED with a simple resistor also require a constant-voltage power source. Constant-voltage configurations are typically used when a constant-current array would require a very high voltage due to a high number of diodes connected in series. Constant-voltage technology is used in applications such as LED fixtures, panels, and strip lights, as well as backlit ad signs, traffic information signs, and large-screen high definition LED displays.

When selecting a constant-voltage driver, make sure that the output current range is higher than the estimated current draw of your LEDs. The feeding current may vary according to the load. The higher the load is, the bigger the current draw becomes, which can affect light output.

We’ve now discussed when, why, and what type of LED driver you need. Next time, we’ll discuss the many other factors involved in choosing LED drivers, such as dimmability, IP-rating, UL class 1 or class 2 designations, efficiency, and power factor. Have any questions about whether or not you need a driver? Feel free to ask us in a comment or drop us a line on FacebookTwitterGoogle PlusLinkedIn, or Pinterest!

Jessica Banke

Jessica graduated with a Creative Writing degree from Texas A&M University in 2013. As a Copywriter for, she uses her writing skills to illuminate the world on lighting topics from A to Z. Check back often for more fun and practical articles!

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