Common Questions and Answers about LED Drivers/Power Supplies
January 19th 2018
LED drivers, or LED power supplies, provide LED light bulbs with the electricity required for peak performance, much like a fluorescent lamp’s magnetic ballast or a low-voltage bulb transformer. The steady stream of technological innovations and the often-confusing terminology can make LED driver selection seem overwhelming even to seasoned professionals. The goal of this article is to answer some of the most common questions and help the lighting designer/specifier navigate the intricate labyrinth of LED driver selection.
- What is an LED driver and why do you need one?
LEDs cannot function without three essential components: the chipset that emits the light; the driver that regulates power to the light source; and the heat sink that cools the unit. The LED driver is a vital component of the technology as LEDs use the power converted by the driver to generate light. These drivers are very efficient in converting electricity, which is why a 100W LED bulb can replace a 400W metal halide bulb. - What is the difference between constant voltage and constant current drivers?
One of the most important factors to consider is whether the application needs a constant voltage (CV) or constant current (CC) power supply. A CV driver supplies a fixed voltage and is suitable for lighting applications where the number of LED strings and current draw are unknown. In these applications, current control is accomplished by additional components at the LED itself. CC drivers supply a fixed current and are suitable for applications that require constant current directly connected to the LED. This type of driver operates within limited voltage ranges, and it is therefore essential to choose a driver with an appropriate voltage rating. GRE Alpha, a leading designer of solid state LED power supplies, offers various dual mode LED drivers for increased lighting design flexibility. - What is an AC LED driver?
The function of an AC LED driver is to step down the input voltage to a lower output voltage to meet the LED’s small voltage needs, usually 12 or 24 Volts. It is important to consider your power requirements as AC LED drivers can only function with bulbs that already have an internal AC to DC converter. - What are PF and PFC and why are they important?
Power Factor (PF) is the relationship between real and apparent power, and represents the ratio between the actual load (kW) and the apparent load (kVA). Power Factor Correction (PFC) is critical to LED driver selection as LEDs, which have a low PF, draw greater current loads than higher PF loads. Low PF leads to more significant power loss in utility lines and LED drivers must therefore meet PFC standards. - Does the driver support dimming and is it flicker-free?
If the application requires any unique features, such as dimming, be sure to select a quality LED driver with flicker-free dimming capabilities. Today’s wireless LED drivers are designed for compatibility with robust wireless protocols such as Bluetooth LE, Zigbee, EnOcean, Thread, Z-Wave and KNX, thus allowing for interference-free near-instantaneous feedback. Designers must understand the various protocols available and compare strengths as well as limitations. - Can I use the driver in my outdoor application?
LED drivers with a rating of IP67, can be utilized in outdoor applications. Products with this rating are fully protected from dust and can withstand water submergence to 1m for up to 30 minutes. - Is the driver compatible with wireless control systems?
Many of today’s lighting control systems must be capable of connecting to the Internet of Things (IoT), the name given to the network of linked wireless physical devices. If your system design calls for wireless connectivity, you must ensure that your LED drivers are wireless and can “speak” the same language as other devices in your system. Connected devices can help designers plan systems that are more energy efficient and intuitive. If your LED driver does not have to “speak” one of the loT connectivity protocols, there are a wide array of LED dimming module add-ons available in the market. These products allow designers added project design choices. “This is one of our core unique innovations with our modular system approach,” said Richard Fong, Director at GRE Alpha. - What is potting (encapsulating) and why is it important?
Potting enhances the IP (Ingress Protection) rating of the driver/power supply by providing a waterproof barrier to protect components from liquids. This is especially critical for outdoor applications. The potting compound also conducts heat away from the vital power components to the surface of the enclosure and thus reduces thermal stress and improves component durability. - What are the benefits of using high power efficiency drivers?
Energy efficiency is the main reason customers hunger for solid state LED lighting control systems. The use of high-efficiency drivers increases the energy savings that can be achieved. Higher efficiency power supplies dissipate less heat and result in improved product lifetime.
- What is the LED driver’s life expectancy?
In addition to energy savings, LED lighting systems must also withstand the test of time. LEDs are known to last significantly longer than traditional lighting systems. Thus the LED power supply must live up to the same life expectancy of the LED. Mean Time Between Failure (MTBF) is a good indicator of LED driver quality. Leading LED driver manufacturers, such as GRE Alpha, list MTBF information on their product data sheets. Lighting system designers can count on the integrity of these components for their system controls.
Other factors to consider are reliability, function, and usability. Not all drivers are alike. Consider the benefits of taking the modular route. The main benefit is that it frees the user to mix and match what they need at the right price without having to over-engineer. To that regard, our modular systems approach is unique. To learn more about LED drivers and power supplies, please visit GREAlpha.com or the referenced articles below.
References
Corrie, A. (January 01, 2013). LED Lighting Depends On Drivers. Electronic Design, New York,
61, 5, 74.
Wang, Y., Alonso, J. M., & Ruan, X. (July 01, 2017). A Review of LED Drivers and Related Technologies. Ieee Transactions on Industrial Electronics, 64, 7, 5754-5765.
Filed in: Industry
