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PWM Dimming

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LEDs can be dimmed in two ways: analog and pulse-width modulation (PWM) dimming. Analog dimming changes LED light output by simply adjusting the DC in the string, while PWM dimming achieves the same effect by varying the duty cycle of a constant current in the string to effectively change the average current in the string.
Pulse-width modulation (PWM) is a common type of dimming used to adjust the current in white-LED driver devices. PWM dimming takes a rectangle waveform with a variable positive duty cycle (D) and adjusts the LED current proportionally.

LED PWM (Pulse width modulation) dimming mode has the following advantages:
1. No LED chormatographic offset is generated the LED always operates between full amplitude current and 0.
2. High dimming accuracy, because the pulse waveform can be completely controlled to high precision, so it is easy to achieve 1/10,000 accuracy.
3. Flicker does not occur even over a wide range of dimming. Because it will not change the working conditions of the constant current source (boost ratio or buck ratio), it is unlikely to overheat and other problems.
4. Can be combined with digital (DALI/DSI/DMX 512) control technology control, because the digital control signal is easy to transform into a PWM signal.

Although LED PWM (Pulse width modulation) dimming mode has many advantages but needs to pay attention to the following two problems:
1. The choice of pulse frequency, because the LED is in a fast switching state, if the working frequency is very low, the human eye will feel flashing. To make full use of the visual residual phenomenon of the human eye, it should operate at a frequency higher than 100Hz, preferably 200Hz.
2. Eliminate the whistling caused by dimming, although the human eye cannot detect it above 200Hz, it is within the range of human hearing until 20kHz. At this time, a "hissing" sound may be heard. There are two ways to solve this problem. One is to increase the switching frequency above 20kHz, out of the range of human hearing. Another way is to find the sound-producing device and deal with it.

We have done a lot of research on the PWM dimming method and designed a variety of series of products, especially the PWM, 0-10V, R three-in-one dimming led driver is the most popular. For example HZD018CVI, it is a high PF and no-flicker dimming power supply, energy-saving and high efficiency, and dimming smooth. We also have PWM dimming products for radar module control. Please click here to contact us for more information.

PWM Dimming (HZD018CVI)

：Triac Dimming ：1-10V/0-10V Led Driver
：Triac Dimming ：1-10V/0-10V Led Driver

PWM Dimming

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