What LED Driver Do I Need?

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 electricity they require to function and perform at their best. As most places run on higher voltage, alternating current, and LEDs run on low voltage, direct current, LEDs require drivers for two purposes:

To convert higher voltage, alternating current to low voltage, direct current
To keep the voltage and current flowing through an LED circuit at its rated level
For the reasons above, all LED light bulbs require a driver. However, some LEDs (such as those designed to replace household bulbs) already contain an internal driver and do not require an external driver. LEDs that typically require an external driver include tape light, cove lights, and downlights, as well as certain fixtures, panels, and outdoor-rated lights. Check your LED’s data sheet to see if your new LED requires an external driver. Usually your LED will already come included with a driver as part of the assembly, or the data sheet will specify the driver you need to purchase.

You may also need to purchase a separate driver when an LED fails before its rated lifetime. When an LED fails prematurely, it is often the fault of the driver. Thus, replacing an LED driver can save you the hassle and cost of unnecessarily replacing a perfectly good LED. Unfortunately, internal drivers cannot be replaced, so if your household LED dies early, you must purchase an entirely new bulb.
What LED driver do I need?
There are three types of LED drivers: constant-current, constant-voltage, and AC LED drivers. The driver you need depends on the operating specifications of your LED. To begin your selection process, look at your LED (or the LED driver that you are replacing) and select the appropriate voltage range.

If one output voltage is specified, you need a constant-voltage driver.
If there is a range of output voltages, you need a constant-current driver.
If an AC voltage input is specified, you need an AC LED driver.