At present the mainstream of LED dimming technology there are 3 main types: by adjusting the drive of a light EMITTING DIODE (LED) light source current to the LED LAMP dimming, the use of thyristor to achieve dimming of the LED lamp and the dimming of the LED lamp through pulse width modulation.
1. The analog dimming
The analog dimming is called linear dimming, which uses the luminous flux of the LED light source and its current approximately linear relationship, and changes the input voltage through the principle of resistance voltage division, and then adjusts the current driving the LED light source to achieve dimming. Analog dimming is inexpensive and easy to implement.
2. The SCR dimming
The thyristor dimming of LED lights is gradually developed and matured in the replacement process of traditional lighting fixtures. SCR was first used in the dimming of traditional lighting lamps such as halogen lamps and incandescent lamps, which is a front-edge phase-controlled dimming. Because halogen lamps and incandescent lamps are purely resistive, there is no need to input a standard sine wave. As long as the effective value of the input voltage can be continuously changed, continuous and smooth dimming can be achieved. The principle is shown in Figure 1 below. SCR dimming technology is efficient and stable.
3. The SCR dimming
PWM dimming is to achieve dimming by changing the time ratio of LED on and off, that is, changing the duty cycle at a certain frequency. The driving principle is observed from the relationship between the duty cycle of the input waveform and the drive current of the LED, they are linearly proportional. Professionally speaking, it is to adjust the duty cycle of PWM to change the input power and output current of the drive circuit, and ultimately achieve the purpose of energy saving and dimming. PWM dimming has many advantages: will not change the color temperature of the LED lamp, smooth dimming and high precision, large dimming range, easy to combine with MCU and intelligent, no flicker, etc.