To get the best performance out of your LED light or array, you're going to want an LED driver. If you're not familiar with the term, an LED driver is a power supply that is self-contained and which has outputs that are matched to your LED or LED array's electrical characteristics.
The Need for LED Drivers
Regardless of their size, type or power, LEDs always work better when they're driven by a consistent, constant current source supply. This is because LED color changes with even the smallest variations in driving current. It's common for LEDs to support a variety of forward voltages and system voltages, which can cause even more variations in the LED color and brightness.
Understanding the Electrical Characteristics
Because this is such a new technology, there are currently no industry standards for LED drivers. That's all the more reason that you need to understand your LED or array's electrical characteristics before you select or design a driver circuit. Your drivers must be current-regulated. This simply means that they should deliver a consistent current through a large range of load voltages. Drivers could also offer pulse-width modulation- or PWM- circuits. In addition, drivers can have more than just a single channel for separate control of various arrays or LEDs.
Two Ways of Regulating Current
Before designing or selecting a driver circuit, you should also know the two ways of controlling forward current. The first is using the LED VI curve in order to determine how much voltage should be applied to the LED to get the forward current that you want. Typically, this is done by applying a voltage source, then using a ballast resister with it. This method has some drawbacks. For starters, a change in LED forward voltage always creates a change in its current. Also, the power dissipation and voltage drop across the ballast resistor is known to reduce battery life and waste power.
The second way of controlling forward current is the preferred method, simply because it addresses the shortcomings of the first one. This second method involves driving the LED by a constant-current source. This source gets rid of changes in current caused by variations in the forward voltage. This in turn creates a constant LED brightness. Generating the needed constant-current source is straightforward and simple. Instead of regulating the output voltage, the voltage is regulated by the input power supply across a current-sense resister.
Note that multiple LEDs need to be connected in any series configuration in order to maintain an identical current flowing through the LEDs.
Manufacturers of LED Drivers
Not surprisingly, some of the same names that you see providing LED lights also provide the drivers for them. It's always a good thing to buy LED products from trusted manufacturers. Some of the better names that you'll encounter frequently include MagTech, LuxDrive, Advance LumiDrives and Lightech. A quick Internet search on any of these names will put you on the road to getting your LED driver needs filled.
|
|