LED is a simple diode that produce light when a current flows through it. The brightness of leds lights is directly related to the current of drivers. An LED almost without resistance, it is necessary that some means of current control or it will burn out. Current-limiting resistor is the simplest method. But this is seems unrealistic for high-power circuits which designed for mains operation, the output of LED light is proportional to the current, that is why we can dim LED lights just the dimming system used is matching well with the dimmable LED transformer, even achieve excellent LED dimming performance.

LED driver characteristics determine different dimming method . Some drivers are designed to be compatible with the phase control systems which be used with incandescent lamps. Because of the inherent characteristics of the drivers, reverse phase control systems become the most common method since reverse phase control can prevents damaging current surges while the power supply running. Due to some reasons, reverse phase dimming does not always provide smooth, predictable dimming to lights. Many LED driver manufacturers customized a separate low-voltage dimmer control which can sends a signal to the driver to increase dimming performance.