Both LEDs and fluorescent lights require a buffer between the lamp and the power supply. While fluorescents use ballasts, LEDs use drivers. Even though the function of ballasts and drivers are quite similar, most documentation prefers 'drivers' to be associated with LED lamps and 'ballasts' to other traditional light sources. Ballasts and drivers are essential components to trigger and control the light fixtures.
What is a Light Ballast?
Almost all lights come with a device to limit the amount of current in its electrical circuit. This device is called a light ballast.
Fluorescent lights operate by generating an arc between the anode and the cathode within the tube. Fluorescent light ballasts facilitates this by providing an initial spike of high voltage and once the light is on, it acts as a current regulator. Even if the lamps are connected to high power sources, the ballast ensures to regulate the energy and avoid a current rise. Without a light fixture ballast, light bulbs and fluorescent lights would cease to function as the risk of current rising to a destructive level is not eliminated. Metal halides, mercury vapor and HID lamps are major examples of lights using ballasts.
What is an LED Driver?
An LED driver, in addition to being a self-contained power supply, regulates the power required for an LED or a number of LEDs.
LEDs are designed to function on a low voltage, DC current. But, given that most places supply higher voltage AC current, a device is needed to rectify this and this is where an LED driver comes to the picture. LED drivers are also responsible for shielding the LEDs from voltage and current fluctuations. Fluctuations can cause the light output to degrade faster due to high temperatures within the LED. There are mainly two types of external LED drivers, constant-current and constant-voltage and then there's a third
type, known as AC LED driver. Each kind of these drivers is designed to light up LEDs with different electrical requirements. Additionally, these drivers could also be designed to make them capable of dimming. Usually, both the LED fixtures and their spec sheets mention if they are dimmable. If they don't mention dimming at all, it is quite safe to assume that the product is not dimmable. The external drivers require an external dimmer or dimming control devices like TRIAC or 1-10 V dimmers to function.