Currently, the most common LED dimming methods in the market include 0/1-10V dimming, phase-cut dimming (also known as TRIAC dimming), and PWM dimming. The dimming process involves controlling the output current, voltage, and frequency to achieve dimming functionality in LED lighting devices. Today, Renerge will explain the principles behind the widely used 0-10V dimming and phase-cut dimming techniques in the lighting industry.
1. LED 0/1-10V Dimming:
0-10V dimming, also known as 0-10V signal dimming, is an analog dimming method. What sets it apart from phase-cut dimming power supplies is the addition of two 0-10V interfaces (+10V and -10V) on the 0-10V power supply. Dimming is achieved by changing the voltage in the range of 0-10V. The light is brightest at 10V and completely off at 0V. In the case of 1-10V dimming, the dimmer ranges from 1V to 10V. When a resistance dimmer is set to the minimum of 1V, the output current is 10%, and at 10V, the output current is 100%, resulting in 100% brightness. It’s important to note that 1-10V dimmers do not have a switch function, meaning they can’t completely turn off the light, whereas 0-10V dimmers do have a switch function.
2. LED Phase-Cut Dimming (Triac Dimming):
Phase-cut dimming, which was previously used for incandescent and energy-saving lamps, is currently the most widely used dimming method for LEDs. Phase-cut dimming is a physical dimming method. It starts from AC phase angle 0, chopping the input voltage until the thyristor conducts. The principle involves cutting the waveform to reduce the effective value of the output voltage, thus lowering the power of common loads (resistive loads). Phase-cut dimmers are known for their high precision, efficiency, small size, light weight, and ease of remote control. They dominate the market due to their high efficiency, stable performance, and low dimming cost.
3. PWM Dimming:
PWM (Pulse Width Modulation) dimming, also known as digital dimming, modulates the ON and OFF time of the LED using PWM waves to adjust the brightness. PWM is a highly effective technique in digital control applications and is widely used in various fields, including measurement, communication, power control, transformation, and LED lighting. By digitally controlling analog circuits with PWM waves, system costs and power consumption can be significantly reduced. Moreover, many microcontrollers and DSPs already include PWM controllers on the chip, making digital control implementation easier. This method takes advantage of the human eye’s reduced sensitivity to flicker at high frequencies. If the frequency of light flickering is above 100 Hz, the human eye perceives it as continuous light, not flickering. PWM adjusts brightness by changing the ratio of ON and OFF time. Within one PWM cycle, because the human eye is not sensitive to light flickering at frequencies higher than 100 Hz, the perceived brightness accumulates. In summary, PWM is a method of digitally encoding analog signal levels. By using a high-resolution counter, the duty cycle of the square wave is modulated to encode a specific analog signal level. PWM signals remain digital because, at any given moment, the full-scale DC supply is either fully present or completely absent. Voltage or current is applied to the analog load in the form of a repeated pulse sequence that is either ON or OFF. Any analog value can be encoded using PWM, provided the bandwidth is sufficient.
These are the differences between 0-10V dimming, phase-cut dimming, and PWM dimming. Feel free to leave comments for further discussion in the comment section below.