A Comprehensive Guide to Lighting Dimming Methods

Lighting Dimming Methods
The Guide to Lighting Control Systems for Home Automation

4 Kinds of Lighting Control Dimming output introduction

Leading-edge dimming

Leading-edge dimming is to use an SCR circuit, starting from AC phase 0, the input voltage is cut, and there is no voltage input until the SCR is turned on. The principle is to adjust the conduction angle of each half-wave of the alternating current to change the sine waveform, thereby changing the effective value of the alternating current, to achieve the purpose of dimming.

  1. Cut in front of the mains sine wave, and automatically close at zero crossing
  2. Generally, the power is relatively large, and the impact current is large. 16A can withstand 600A in 20ms
  3. With a dimming LED driver, the general discount is relatively large. Rated 500W can only take 300W or less
  4. The dimming effect is relatively good. General IC drivers are optimized for the characteristics of leading-edge dimming
  5. There is a certain disturbance to the power grid.

Trailing-edge dimming

Made with Field Effect Transistor (FET) or Insulated Gate Bipolar Transistor (IGBT) devices. The conduction is controlled by the MOS tube to realize dimming. So the cost is higher. MOSFET is a fully controlled switch, which can be controlled both on and off, so there is no phenomenon that the thyristor dimmer cannot be completely turned off. In addition, MOS dimming circuits are more suitable for capacitive loads than SCR.

  1. Back-edge dimming, zero-crossing conduction, cut behind the mains sine wave
  2. Generally, the power is not too large, and it is not resistant to inrush current. Generally at 100-200A
  3. Low discount with LED driver
  4. The dimming effect is general
  5. There is almost no disturbance to the power grid.

1-10V、0-10V Dimming

It is essentially PWM dimming. The dimming is realized by changing the PWM duty cycle by changing the voltage on the signal line. Compared with phase-cut dimming, the advantages are that the lamps have good matching compatibility, a smooth dimming curve, no noise, and no noise. Flickering, etc.; but the wiring is a little complicated. When wiring according to the strong current of the loop, additional signal lines are required; and compared with DALI dimming, 0/1-10V dimming cannot achieve single-light control, and it is impossible to control the light in the later stage. The loop is adjusted, and the corresponding attenuation of the 0/1-10V voltage on the change of the signal line length is also a problem to be considered when planning the line in the early stage. 

PWM Dimming

PWM is a digital dimming signal that controls the light on or off by controlling the duty cycle within a cycle. The general frequency of PWM is above 240Hz. When the frequency reaches 3.2KHz, it can be defined as no flicker. There are two solutions on the market, they are constant voltage and constant current.  Because the constant voltage mode can be paralleled arbitrarily when the driver current allows. Very easy to install and plan the number of luminaires. At the same time, it is easy to find faulty lamps when the lamps are damaged. It is more popular among users. The constant current method can only be installed in series. If one lamp is damaged, the lights on the entire circuit will not light up, which is not conducive to troubleshooting.


  1. The driving voltage is constant
  2. The current depends on the power supply itself
  3. When the current allows, it can be connected in parallel arbitrarily
  4. Generally used in light strips and other products, the power is relatively large. At present, the main products on the market are light strips, and TILLUME has also developed some LED spot modules to replace MR16. 


  1. Drive current constant current
  2. The voltage depends on the maximum output voltage of the power supply
  3. When the current allows, it can be connected in series arbitrarily
  4. Carefully parallel