The leading edge dimming is to use a thyristor circuit. From the AC phase 0, the input voltage is chopped until the thyristor turns on. The principle is to adjust the conduction angle of each half-wave of the alternating current to change the sinusoidal waveform, thereby changing the effective value of the alternating current, so as to achieve the purpose of dimming.
Leading-edge dimmers have the advantages of high adjustment accuracy, high efficiency, small size, light weight, and easy remote control. They dominate the market, and most manufacturers' products are dimmers of this type. Leading-edge phase control dimmers typically use thyristors as switching devices, so they are also called thyristor dimmers.
The advantages of using an FPC dimmer on LED lighting are: low dimming cost, compatibility with existing lines, and no need to re-route the trim along the phase cut control. The disadvantage is that the dimming performance of the FPC is poor, which usually leads to a reduction in the dimming range and results in the minimum required load exceeding the rated power of a single or small number of LED lights. Because of the properties of the thyristor's semi-controlled switch, only the function of turning on the current can not completely shut off the current, even if the minimum current is still low, and the characteristics of the LED micro-current emission, making the use of thyristor to dim a lot of existence After turning off the LED, there is still a phenomenon of weak light emission, which has become a difficult problem in the promotion of the dimming method of this wiring-free LED. E-Linker's professionally developed cutting-edge phase-cut LED dimming driver solves this problem and optimizes the “C-TURN OFF” technology of the drive circuit to avoid problems such as “closed off” and “strobbling”. Matching E-Linker's easy-to-connect phase-cut LED dimming driver can perfectly match with other thyristor dimming systems, saving users the wire and wiring man-hours and solving the SCR LED dimming matching and not Shut off the chaotic pattern.
Back-porch phase-cut control dimmers are fabricated using field-effect transistor (FET) or insulated-gate bipolar transistor (IGBT) devices. Back-porch phase-cut dimmers typically use MOSFETs as switching devices, and are also referred to as MOSFET dimmers, commonly known as "MOS transistors." The MOSFET is a fully-controlled switch that can be controlled either on or off, so there is no phenomenon that the thyristor dimmer cannot be completely turned off. The MOSFET dimming circuit is more suitable for capacitive load dimming than the thyristor, but due to the high cost and the dimming circuit is relatively complex and is not easy to be stable, the MOS tube dimming method is not developed, and the thyristor modulation is not developed. Optical devices still occupy most of the dimming system market.
Compared with leading-edge phase-cut dimmers, trailing-edge phase-cut dimmers are used in LED lighting devices. Because there is no minimum load requirement, better performance can be achieved on a single lighting device or a very small load, however, Because MOS tubes are rarely used in dimming systems, they are generally made as knob-type single-lamp dimming switches. This low-power rear phase-cut dimmer is not suitable for engineering applications. Many lighting manufacturers use this kind of dimmer to do dimming tests on their own dimming drivers and lamps. Then, the company's own dimming products were brought to the engineering market, resulting in the frequent occurrence of phase-cut dimming driven by the SCR dimming system. This mismatch in dimming causes dimming flicker, which can quickly damage the power supply or dimmer.