PWM stands for Pulse Width Modulation, and PWM dimming is a technique used to control the brightness of a light or the speed of a motor by varying the duty cycle of a pulse waveform. In the context of dimming, PWM is commonly used for controlling the brightness of LEDs (Light Emitting Diodes) in various electronic devices such as LED lights, computer monitors, and display screens.
Here’s how PWM dimming works:
- Pulse Generation: A square wave, often referred to as a pulse waveform, is generated. This waveform consists of a series of pulses with a fixed frequency.
- Duty Cycle: The duty cycle is the percentage of time the signal is high (on) compared to the total time of one cycle. It determines how much time the signal is in the high state versus the low state. In the context of PWM dimming, adjusting the duty cycle controls the amount of time the LED is on versus off.
- Brightness Control: When the duty cycle is increased, the LED is on for a longer duration during each cycle, resulting in increased brightness. Conversely, decreasing the duty cycle reduces the on-time, causing the LED to appear dimmer.
- Perceived Dimming: To the human eye, this rapid switching on and off of the LED at a high frequency (typically above the flicker fusion threshold) is imperceptible, and the LED appears to be emitting light continuously, but at a lower intensity.
PWM dimming is popular because it is a simple and efficient way to control brightness. It allows for precise control and is widely used in applications where dimming control is essential, such as in energy-efficient lighting systems or devices where dynamic brightness adjustments are required.