LED drivers are an essential component of LED technology. With numerous types and variations available, it can be overwhelming to choose the right one. This article aims to demystify LED drivers by explaining their varieties, differences, and factors to consider when selecting one for your lighting application.

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What is an LED Driver?

An LED driver is an electrical device that regulates power to an LED or a string of LEDs. It is a crucial part of an LED circuit, and operating without one can result in system failure. The LED driver ensures the proper function of LEDs by compensating for changes in forward voltage and delivering a constant current.

Using an LED driver is vital to prevent damage to LEDs. The forward voltage (Vf) of high-power LEDs changes with temperature. As the temperature increases, the forward voltage decreases, causing the LED to draw more current. This can lead to thermal runaway, where the LED gets hotter and draws even more current until it burns out. A constant current LED driver helps avoid thermal runaway by compensating for changes in the forward voltage while providing a steady current to the LED.

Things to Consider Before Selecting an LED Driver

Before choosing an LED driver, there are several factors to consider:

1. LED Specifications: Determine the type of LEDs being used, their forward voltage, recommended driving current, and other specifications.

2. Constant Current vs. Constant Voltage: Determine whether you need a constant current LED driver or a constant voltage LED driver. Each has its own advantages and applications.

3. Power Source: Consider the type of power source for your application (DC, AC, batteries, etc.). Understanding power source compatibility is crucial in selecting the right LED driver.

4. Space Limitations: Evaluate the available space for the LED driver installation. Consider voltage limitations and size restrictions.

5. Application Goals: Identify the main goals of your lighting application, such as size, cost, efficiency, performance, etc.

6. Special Features: Determine if any special features are required, such as dimming, pulsing, or microprocessor control.

Types of LED Drivers

LED drivers can be categorized into two main types: those that use low voltage DC input power (5-36VDC) and those that use high voltage AC input power (90-277VAC). LED drivers utilizing high-voltage AC power are known as Off-Line drivers or AC LED drivers.

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For most applications, it is recommended to use low voltage DC input LED drivers. Even if the input power is high voltage AC, using an additional switching power supply can convert it to DC input for the LED driver. Low voltage DC drivers are more efficient and offer more dimming and output options for smaller applications. However, for large general lighting projects in residential or commercial settings, AC drivers may be better suited.

Dimming Options for LEDs

Dimming LEDs depends on the type of power source used. Here are the dimming options for both DC and AC power:

DC Dimming

Low voltage DC powered drivers can be dimmed in two different ways. The simplest method is using a potentiometer, which allows for a full range of 0-100% dimming. If multiple drivers are being dimmed from one potentiometer, the potentiometer value can be determined by dividing its value by the number of drivers.

Another option for DC dimming is using a 0-10V wall dimmer, which can work with several drivers simultaneously. The dimming wires are connected directly to the driver’s input.

AC Dimming

For high voltage AC power drivers, dimming can be achieved through 0-10V dimming or TRIAC dimming. Many AC drivers support 0-10V dimming, making them compatible with various leading-edge and trailing-edge dimmers like Lutron and Leviton.

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Determining the Number of LEDs for a Driver

The maximum number of LEDs that can be powered by a single driver is determined by dividing the maximum output voltage of the driver by the forward voltage of the LEDs. For example, using LuxDrive drivers, the maximum output voltage is obtained by subtracting 2 volts from the input voltage.

Determining Power Requirements

To determine the input voltage for the LED driver, the following formula can be used: Vo + (Vf x LEDn) = Vin.

In addition to voltage calculations, it is crucial to consider the wattage required for the LED circuit. The wattage can be calculated by multiplying the forward voltage (Vf) of the LEDs with the drive current (in Amps). Adding a 20% cushion to the calculated wattage is recommended to prevent power supply overwork and potential LED flickering or premature failure.

LED Boost Driver: FlexBlock

The FlexBlock LED drivers are boost drivers, capable of outputting a higher voltage than the input voltage. This feature allows for the powering of more LEDs in-series with a single driver. The maximum number of LEDs that can be powered depends on the maximum output voltage of the driver and the forward voltage of the LEDs.

Resources for Choosing the Right LED Driver

To assist in selecting the appropriate LED driver, various tools and resources are available. LEDSupply offers a Driver Selector tool that helps determine the ideal driver based on circuit specifications. Additionally, LEDdynamics’ LUXdrive division provides custom LED driver design and manufacturing services.

For further inquiries and assistance, you can contact LEDSupply at (802) 728-6031 or sales@LEDsupply.com.

In conclusion, understanding the different types of LED drivers and considering key factors such as LED specifications, power source, and application requirements are crucial in choosing the right LED driver. With the right driver, your LED lighting application can achieve optimal performance and efficiency.