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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Pulse-width modulation (PWM) controls a signal by changing how long each repeating digital pulse stays on. That on-time, expressed as a fraction of the cycle, is the duty cycle; in many power-control circuits, a higher duty cycle delivers more average power to the load.
What is PWM duty cycle?
A PWM waveform repeats an on portion and an off portion. Duty cycle is the share of each cycle spent on, usually written as a percentage.
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- 25% duty cycle: the signal is on for one quarter of each cycle.
- 50% duty cycle: it is on for half of each cycle.
- 75% duty cycle: it is on for three quarters of each cycle.
For example, a 50% duty-cycle waveform is high for half its period and low for the other half. Raising duty cycle at a fixed period lengthens the on-time; it does not change the number of cycles per second.
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How do PWM period and frequency relate?
The period is the time taken by one complete cycle, measured from one rising edge to the next. Frequency is the number of cycles per second, and it is the reciprocal of period: period = 1 ÷ frequency. A 1 kHz PWM signal has a period of 1 millisecond, according to Microchip Technology’s 2023 explanation of PWM on 8-bit PIC devices.
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Duty cycle and frequency describe different properties. Duty cycle sets the on-time fraction within a cycle; frequency determines how often that cycle repeats. A circuit can change one while holding the other fixed, subject to the hardware and application.
How does PWM control an LED or motor?
In a common power-control arrangement, a switching device turns a load on and off rapidly. Changing the duty cycle changes the fraction of time the switch is on, which can change the average power delivered. PWM is used in motor control, LED lighting and power supplies, among other applications, as Microchip notes in its PWM overview.
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- Supports 6pcs 4 Pin PWM Fans (Fans not included, Not compatible with 3-pin/2-pin fans)
- Flexible Power Supply Input: Compatible with both Type-C 12V (Supports QC3.0 / PD3.0) and DC 5.5×2.1mm (5521) 12V input, allowing flexible power options
- Maximum total power output: 60W (5A@12V), with each port supporting up to 2A current while total combined current shall not exceed 5A
- Adjustable PWM duty cycle: 10 lights represent PWM duty cycle (0-100% in 10% increments), the color of indicator light shows input voltage status. ( Blue light: 12V input normal. Orange light: Input voltage below 11.8V, fan operates at low speed. Red light: Input voltage below 8.4V, your power device unusable.)
- Package include: a 4 Pin 12V PWM Fan Speed Controller ONLY
LED lighting
For an LED circuit designed for PWM dimming, changing the duty cycle changes the average drive over time and therefore the apparent brightness. The exact result depends on the LED driver and circuit; the duty-cycle percentage is not a universal brightness percentage.
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For a motor, PWM can regulate the power supplied through a drive circuit, affecting motor speed. The motor’s inductance, the drive electronics and the PWM frequency all influence how the switching waveform translates into motor behavior. A 50% duty cycle therefore does not guarantee that a particular motor runs at half speed.
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- 8-way fan splitter board for powering, controlling and monitoring multiple fans, transmits PWM signal from PC motherboards or optional NA-FC1 fan controller to all connected fans
- 4-pin (for 5V and 12V fans) and S-ATA (for 12V only) inputs can be used simultaneously (power via S-ATA, RPM & PWM via 4-pin), safety fuses provide protection against overcurrent and short-circuits
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In either example, the PWM signal is a control method, not a promise that the load receives a fixed voltage equal to the duty-cycle percentage of the supply. The circuit topology and load determine the actual voltage and current behavior.
Does PWM produce an analog voltage?
A PWM output pin produces a digital waveform that switches between its low and high levels; it is not automatically a steady analog-voltage output. An RC low-pass filter can average the pulses into an approximate voltage, a low-cost digital-to-analog approach described by Microchip’s PWM documentation. The resulting voltage depends on the waveform and filter, and filtering smooths rather than changing the raw pin into an analog source.
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- Supports 6pcs 4 Pin PWM Fans (Fans not included, Not compatible with 3-pin/2-pin fans)
- Flexible Power Supply Input: Compatible with both SATA 12V and DC 5.5×2.5mm (5525) 12V input, allowing flexible power options
- Maximum total power output: 60W (5A@12V), with each port supporting up to 2A current while total combined current shall not exceed 5A
- Adjustable PWM duty cycle: 1%–99%
- Package include: a 4 Pin 12V PWM Fan Speed Controller ONLY
Edge-aligned and center-aligned PWM
PWM implementations can differ in how pulses are positioned within the period. Microchip distinguishes two common timing alignments:
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- Edge-aligned PWM: pulses are aligned to an edge of the period. Microchip describes this mode as offering simple configuration, fast response and higher resolution in the context of its device documentation.
- Center-aligned PWM: pulses are positioned around the center of the period. Microchip identifies it as useful for reducing harmonics in some applications.
These are application-dependent implementation tradeoffs, not a universal ranking. Available modes, duty-cycle resolution and configuration depend on the microcontroller’s PWM peripheral. Choose settings based on the specific MCU, load and control requirements, and check the device datasheet for supported features.
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- Includes a 3-way splitter cable for controlling up to 3 fans simultaneously
- 6-year manufacturer’s warranty
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