Pulse-width modulation involves varying the duty cycle of a high-frequency square wave to control the average voltage or current delivered to a load. By changing how long the signal stays high versus low during each cycle, it efficiently drives motors, dims LEDs, and regulates power supplies without the massive heat losses of linear regulation.
The fan is way too loud at full speed, so let's drop the PWM duty cycle to 40 percent.
When using PWM to dim LEDs, keep the frequency above a few kilohertz. Lower frequencies can cause visible flicker or a stroboscopic effect that strains the eyes.
Related terms
Duty cycle
The percentage of time a periodic signal is active compared to its total period.
SMPS
A switched-mode power supply uses high-frequency switching to efficiently convert electrical power.
Power electronics
The branch of electrical engineering focused on the conversion and control of electric power.