First–The terms “LED driver” and “LED power supply” are used interchangeably. Conventional AC-DC power supplies and DC-DC converters provide an output that is regulated to provide a “constant-voltage.” However, LEDs work most efficiently and safest with a “constant-current” . As a result, many new devices have been developed to provide this type of LED drive.
Without the right LED driver, LEDs will become too hot and unstable, causing malfunctions and poor performance. In order to ensure the LEDs function perfectly, the self-contained LED driver needs to provide a constant power supply for the LED. The important thing to keep in mind is whether the output of the power device provides a “constant-voltage” or a “constant current”, they are required by the LED device that is receiving the power.
I did this research because I aquired several led drivers that are 24 volts. I needed a 24 volt power supply for a project and wanted to know if I could use them.
Here is a little more info on led power.
Cheaper LED circuits restrain the current passing through the LED with a simple resistor. In this case, a “constant-voltage” power source is needed. Other examples of “constant-voltage” supplies application includes light-up ad signs, traffic information guide signs, HD LED displaying screens, etc.
“Constant-voltage” drivers come in a variety forms. Some of them look just like a ordinary power supply and some can be used in enclosed fixtures for using in wet and humid environments.
When do I need a “constant-current” driver? For LED that did not include an internal “constant-current” driver in its light modules, an additional external LED driver or power supply will be needed for regulating the current. “constant-current” LED drivers are available in different package and forms, from enclosed moisture-proof packages to integrated circuits to fulfill each applications and output power requirements.
When LEDs are connected together in series, the forward voltage drop for each LED in the group are additive. For example, when 15 LEDs were put in a series and each of the LEDs has a voltage drop of 3V, you will need a voltage source of 45V (15 x 3V=45V) in order to provide the voltage needed for the LED device to operate normally. This is how “constant-current” drivers always include the output voltage range it’s capable of for overcoming the voltage drops in their specification.
Advantage of using a constant current LED driver
So when you’re building your own fixture or working with our high powered LEDs, it is of your best interest to use constant current drivers because:
- They avoid violating the maximum current specified for the LEDs, therefore avoiding burnout/thermal runaway.
- They are easier for designers to control applications, and help create a light with more consistent brightness.
Advantage of using a constant voltage LED driver
You use a constant voltage LED driver only when using an LED or array that has been specified to take a certain voltage. This is helpful as:
- Constant voltage is a much more familiar technology for the design and installation engineers.
- The cost of these systems can be lower, especially in larger scale applications.