The motor will be supplied with 12 V throughout, however, the duty cycle of the PWM signal decides how long the fan should be running or not. The duty cycle of the PWM signal controls the speed of the fan motor. When the PWM signal is high, the motor runs, otherwise, the motor is stationary. The PWM signal can start or stop the motor, depending on the high and low state of it. The PWM control signals are square waves of high frequency, usually 25kHz or above, to make the noise from the fan above the audible human range. The control input is usually an open-drain or open-collector output with a 5 V or 3.3 V pull-up. The PWM signal is the control input of the PWM fan.
PWM fans are 4-pin fans where the fourth wire sends a PWM signal to the fan motor. Pulse width modulation (PWM) fans are DC fans with an extra wire for PWM. Nowadays, standalone fan controllers with knobs are available for this type of DC fan speed control. If the resistor connected is a variable one, the fan speed can be varied until it stalls at a minimum threshold voltage.
Quiet 3 pin fans series#
The voltage drop across the series resistor reduces the voltage reaching the fan supply pin, automatically slowing the speed of the fan. For continuous spinning motion, this minimum voltage needs to be supplied.ĭC voltage control is the method to vary DC fan speed and this can be implemented by incorporating resistances in the supply wire. All the DC fans are specified with a minimum threshold voltage rating if the voltage falls below the threshold, the fan starts to stall. There are still limitations in the percentage decrease in the speed of DC fans. The DC power supply can be reduced below 12 V for lower speeds. If you want to vary the speed of DC fans, the only option is to vary the input DC supply. Some computers monitor the signal pin and signal an alert when the fan operation fails. The signal pin collects the information about the rotation speed of the fan (tachometer output) even when there is no speed control implemented. In DC fans, the power supply can be from a regulated DC source or from the motherboard header pins. The 3 pins are the supply pin (usually 12 V DC), ground pin, and a signal pin.
These fans are also called 3-pin fans, as they come with 3 pins. Generally, DC fans are used as chassis fans with low power consumption. The speed control of cooling fans is a much-debated topic and PWM fans and DC fans are the most frequently discussed solutions. However, if the laptop is extremely hot, the computer might even need additional fans.
Quiet 3 pin fans full#
When the laptop’s heat is less, there is not much need to run the fan at full speed. This variation in heat dissipation often leads to questions on cooling fans and their speed. When you are working on a laptop, you might observe variations in the heat produced. Here, we discuss two types of cooling fans- Pulse Width Modulated (PWM) fans and DC fans. They also aid the working of heat sinks by distributing air across them. The fans in computers gather cool air from the ambient and expel the warm air outside. All computers have built-in fans, as they are one of the approved cooling mechanisms for processors. The PWM signal is the control input of the PWM fan.Ĭooling fans are a vital part of computer hardware, as they cool the CPU and ventilate casing, enabling active cooling in computers. PWM fans are 4-pin fans, where the fourth wire sends a PWM signal to the fan motor. PWM fans are DC fans with an extra wire for PWM. These fans are also called 3-pin fans, as they come with 3 pins: a supply pin (usually 12 V DC), a ground pin, and a signal pin. Cooling fans are a vital part of computer hardware, as they cool the CPU and ventilate casing.ĭC fans are supplied with DC power from regulated DC supply or motherboard header pins.
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