How does LED dimming power work?
As a constant current source, LED is naturally dimmable. The current flowing through the LED beads determines the light output, and their brightness can be adjusted simply by controlling the current of the semiconductor material layer attached to the substrate.
Unlike traditional light sources, dimming does not affect the efficiency and life of LEDs, according to the lighting project manager at the DOE Office of building technology.
In fact, dimming can reduce their operating temperature and extend the life of LEDs. Our dimming methods are usually divided into two kinds: voltage dimming and current dimming. Voltage dimming is to adjust the input voltage of the light source, so as to achieve the purpose of adjusting the brightness of the light source. However, this dimming method is not particularly reliable in the dimming system of energy-saving lamps, but it has obvious effect in LED and incandescent lamps. Current dimming is to adjust the current through the light source, so as to achieve the purpose of dimming. This is a very suitable way for LED dimming. PWM is generally used in LED dimming.
Any LED device, if it is to be a replacement light source or LED lamp, needs a driver to realize dimming. Because the dimming system of LED is low voltage DC source, led needs electronic driver to convert AC into usable and adjustable DC current. These drivers are divided into two dimming modes. In pulse width modulation (PWM), the current through the LED is switched on and off at a very high frequency, "usually thousands of times per second". The current passing through the LED is equal to the average value of the current in the LED switch cycle. By reducing the power on time of the LED, the average current or effective current can be reduced, and then the brightness of the LED can be reduced.