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.
There are two main kinds of external LED drivers, constant-current and constant-voltage, and that the driver you need depends on whether or not your LED light source already includes a constant-current driver within the light (if so, you would need a constant-voltage driver; if not, you need a separate constant-current driver). Now that you’re certain your LED light requires an external driver as well as what type, it's time to narrow down to the specs you need to consider when making a purchasing decision. Here are four factors that will help you make the right selection.1. Power requirements
First, consider the voltage requirements of your lamp. If your LED requires 12 volts to operate, use a 12-volt driver; if using 24 volts, use a 24-volt driver, etc. When selecting a high quality LED driver for a constant-current LED, you must also consider the LED's current output, measured in amps or milliamps. In short, make sure your driver is capable of achieving power output within the specified range of your lamp: consider the voltage and current range of a constant-current driver, and the simple voltage range of a constant-voltage driver.
Next, consider the voltage supply at the location where you will be using the lamp. Your driver must accept the input voltage where you will be using the lamp so that it can properly step it down to the correct output voltage. Traditional homes offer 120 volts as standard, and most commercial or industrial businesses offer 277 volts, but if you're not sure, it's best to consult an electrician. Most drivers accept a wide range of input voltages. Again, you must also consider the current input to the LED when selecting a driver for a constant-current LED.
Finally, consider the wattage requirements of your lamp. Choose a driver with a maximum wattage higher than the lamp wattage. Do not pair the driver with a lamp that exceeds the maximum wattage of the driver or use a lamp that is less than 50% of the maximum wattage of the driver.2. Dimming
Both constant-current and constant-voltage LEDs and drivers can have dimming capabilities, but both must specify that they are dimmable in the product data sheet to make that statement. If the specification does not mention dimming at all, it is safe to assume that the product is not dimmable, and the same is true for home LEDs with internal drivers. Dimmable external drivers usually require an external dimmer or other dimming control device specified in the product data sheet to work.3. Efficiency
Another key characteristic in choosing an LED driver is efficiency. Efficiency, expressed as a percentage, tells you how much input power the driver can actually use to power the LED. Typical efficiencies range from 80-85%, but UL Class 1 drivers that can run more LEDs are typically more efficient.4. Power Factor
The last major feature to consider is the power factor of the driver. The power factor tells you how much of the actual power load the driver is applying to the grid. The power factor can range from -1 to 1. The closer the power factor is to 1, the more efficient the driver is. The conventional standard for power factor is 0.9 or higher. If the power factor is not mentioned in the driver specification, it means that the device has a low power factor, below 0.9.