What is PWM (pulse width modulation) dimmingTime:2021-04-12 / Read:516
There are currently two ways of LED dimming: one is to linearly adjust the LED current (ie, analog dimming), and the other is to use a switching circuit to work at a frequency high enough for the human eye to change the average value of the light output (digital Dimming) is also PWM dimming.
How to realize PWM dimming? How does PWM dimming work?
A MOS tube is connected in series with the LED load. The anode of this series of LEDs is powered by a constant current power supply, and then a PWM signal is applied to the gate of the MOS tube to quickly switch the series of LEDs to achieve dimming. PWM dimming has advantages and disadvantages;
What are the advantages of PWM?
a. Because the pulse waveform can be controlled to an accuracy of one ten thousandth, the PWM dimming accuracy is extremely high.
b. Any number can be quickly transformed into a PWM signal, which can be combined with digital control technology to control dimming.
c. Because the LED works between full amplitude current and 0, PWM dimming will not produce chromatic aberration.
d. Since constant current boost or buck will not cause overheating, even if PWM has a wide range of dimming, the LED will not flicker.
What are the disadvantages of PWM dimming?
Generally, LED drivers are based on the principle of switching power supply. If the frequency of PWM dimming is between 200~20kHz, the inductance and output capacitor around the LED dimming power supply are prone to audible noise.
When PWM dimming is performed, the closer the frequency of the adjustment signal is to the frequency of the gate control signal of the LED driver chip, the worse the linear effect. Therefore, the energy-saving effect of PWM dimming is worse than that of analog dimming.
Generally speaking, PWM dimming is better than analog dimming, because of its overall current control, the brightness of the lamp is more uniform.