Computer fan pwm frequency the speed of the fan. 0” just an fyi //// Now if I understand you correctly I can unplug the DDC PWM wire plug it into the Siverstone PWM fan hub and then Un plug the Silverstone PWM wire from CPU OP and RE plug 3-pin pc fan control. com) PWM Control for PC Fans AN-CM-248 Abstract This Application Note details how Renesas Electronics built a fully-featured 12 V PC fan PWM controller with GreenPAK™ programmable mixed-signal ASICs. But PWMing the fan and therefore the internal commutation It depends on a fan. For DC motors, lower PWM frequency means higher torque at lower speeds. 4-pin fans should be controlled with 25kHz PWM, which is an Intel CPU fan standard. The PWM input is designed to be driven from an open collector output, and the Intel specification calls for the PWM frequency to be between 21kHz and 28kHz, see Motherboard Form Factors. f. Real-world Applications. Speed vs PWM Control Signal: (at rated voltage 48V; PWM signal with 3. High PWM frequency will ensure quiet operation. At default settings with Coding Badly's excellent arduino port I got 500hz from pin0 and 1khz from pin1. Dec 26, 2018 · The most popular protocol by far is a 25 kHz PWM signal to change fan speed. PWM regulates the voltage signal between fully on and fully off, controlling the speed of a fan. com/ScienceFun4uIn a previous tutorial, I showed you how to control 2-wire, 3-wire, and 4-wire CPU fans u Dec 23, 2017 · Intel recommends a PWM frequency of ~25kHz (outside of our hearing range) for 4-pin CPU fans. That is precisely what the circuit below will do: (image from overclockers. Not necessarily, if you have tight voltage control/a controller that reads the fan RPM and adjusts voltage, you can get pretty precise fan speeds. The fan may continue to run at speeds below the minimum speed, but will not start at that speed Jul 17, 2024 · PWM Fans or 4-Pin Fans. Benefits of Using PWM Fans in Your PC. Let’s see what is the Arduino spitting out: 490 Hz (pins 5 and 6: 980 Hz) Arduino analogWrite() Reference; Oh dear. After lowering the PWM frequency, the noise is inaudible at higher speeds. Fan assemblies with this When it comes to most PC fans, they are powered by a constant load of 12v. I recommend getting high quality fans if you care about noise and need to move a lot of air. pulseIn will not work if the PWM duty cycle goes below 25%. Assume the PWM frequency is around 25 kHz, and that the MOSFET can easily switch at that frequency. Pulse width modulation (PWM) fans are DC fans with an extra wire for PWM. PWM Duty cycle Example Min. 3 pin fans want a high pwm frequency on 3rd pin i think. Here are a few application examples of PWM control fan. 2：PWM Manually mode . This is the tricky part. When driving the PWM input of a 4-wire fan, there is usually a recommended PWM frequency for that particular fan listed in the fan’s datasheet. 5A, 12V brushless DC fans. Jun 10, 2012 · I've successfully PWM'd a fan, AFAIR it was an Arctic F8 PWM. These are not PWM fans (i. Fan speed response to this signal shall be a continuous and monotonic function of the duty cycle of the signal, from 100% to the minimum specified RPM. Using PWM to crank the fan all the way up to maximum speed, we’d set the Duty Cycle to 100%. The same PWM signal used to control 4-pin fans can be used to drive the mosfet and control 3-pin fan instead. As for the frequency, I just googled "pc fan pwm frequency". (Frequency in HZ!) (Set currently to 25kHZ) 5 const word TCNT1_TOP = 16000000 / (2 * PWM Jan 5, 2021 · A 5V PWM signal? Finally something made for our Arduino 5V logic world! We’ve got 6 PWM outputs. Figure 7. How does PWM work for PC fans? A QX120 fan can run at a maximum of 2,400 RPM and a minimum of 400 RPM. Most 4-pin fans do work ok on the default 500Hz or 1kHz Arduino PWM frequency. The external control circuit is simpler with high-frequency PWM, but it can only be used with 4-wire fans. 3), the square wave type PWM signal has to be supplied to the PWM input (pin 4) of the fan and must conform to the following specifications: • Target frequency: 25kHz, acceptable range 21kHz to 28kHz Sense (or tachometer) output from fan – outputs a signal that pulses twice for each revolution of the fan as a pulse train, with the signal frequency proportional to the fan speed; Control input – a pulse-width modulation (PWM) input signal, used when the cooling fan assembly has an internal motor driver circuit. Previously, I had fans just switching on and off, and they were pretty noisy and gave little control of Apr 15, 2023 · Old PCs with 2-pin and 3-pin fan controllers are usually used 30Hz PWM. Oct 24, 2016 · CPU Fan Mode Setting（CPU风扇设置） 可选 1：Full On mode . All you have to do is send a square wave at this frequency to the fan, and the duty cycle will determine the fan speed. PWM fans are great for making your PC’s cooling system better. These fans take a PWM signal on their 4th pin to control the speed of the fan, from the spec's of the fan it says it requires/expects: The following requirements are measured at the PWM (control) pin of the fan cable connector: PWM Frequency: Target frequency 25 kHz, acceptable operational range 21 kHz to 28 kHz Maximum Aug 18, 2020 · Another option is to put a R-C filter in series with the fan so that the PWM gets smoothed out and you drive the fan with a variable voltage. Connect a resistor of between10 and about 200 ohms between the Duet fan output and the fan. I wanted a simple speed control of a computer fan (or multiple fans) for temp control of a data cabinet. PWM fans can operate at very low speeds, often in the range of 500-1000 RPM, making them ideal for silent operation. One circut for this that is widely cited is the 556 based circuit located far down on this page. PWMコントロール機能とは，「Pulse Width Modulation（パルス幅変調）」を用いた制御機能であり， コントロール端子-GND間に入力するパルス信号のデューティ比を変化させることにより，ファンの回転速度を外部からコントロールする機能 です。 Aug 29, 2019 · \$\begingroup\$ Even 4-pin PC fans require the motherboard to read the fan speed signal for closed loop control. Also connect a capacitor of at least 100uF in parallel with the motor. The fan's PWM frequency is fixed to the fan by design and user can not change. Any 12v PWM-controllable fan should work. By using some timer tricks, we can make it generate 3 PWM signals at the correct frequency. But we don’t want the fan to be at max speed all the time. 1，开机就全速运转，声音最大。而且一直全速运转。 2，将有CPU Fan PWM Control项，此项可更改数值0-127，对应风扇转速的128个等级，数值越大，风扇转 速越高，声音也越大。 Mar 4, 2017 · I'm looking at building a 4-wire PC fan PWM circuit. Jan 27, 2025 · PWM Control: For the most effective use of PWM, ensure that the chosen fans support PWM operation, typically using a four-pin connector designed for this purpose. Choosing the appropriate frequency for this method can be somewhat tricky. PWM fans have advanced cooling solutions, deliver best performance and greater effciency. Voltage and PWM control methods predate computer fans by a long time. Circuit for driving a fan with high-frequency PWM. To do this just add this line to the relevant fan section How does PWM work for PC fans? A QX120 fan can run at a maximum of 2,400 RPM and a minimum of 400 RPM. The only advantage over 3-pin fans is that fan speed regulation is done with PWM - and lower losses - vs. PWM technology responds quickly and with accuracy. Nov 13, 2019 · Control the speed of your PWM fan easily. 3. 3 VDC TTL; Frequency: 2K Hz; Temperature: 25C) * Above referenced part number AFB0648EH-TP27 The PWM Advantage PWM regulates the voltage signal between fully on and fully off, controlling the speed of a fan. Although these fans are relatively new to the market, they are rapidly becoming more popular. EMC2101 Fan Controller and Temperature sensor ¶ Join Science Fun on Facebook @ https://www. How to Identify a PWM Fan vs Non-PWM Fan? A PWM fan typically uses a small 4-pin connector. Tested using a 12v fan. You should ramp up you're PWM frequency for this. Before lowering the PWM, the sound from the fan was a loud "WHEEEEEeeeeeeeee" sound at any speed other than full speed. This article delves into the world of Fan PWM, exploring its inner workings, benefits, applications, and future trends. Frequency is only 16hz. The PWM signal is the control input of the PWM fan. Jan 31, 2024 · Hi, So "PC" 12v DC 4-wire PWM (signal wire frequency 25khz) fans, what would be the best way to control and monitor (tach wire) these fans over a TCPIP network, I want to replace the noisy AC single-speed, always-on fans in my inverter enclosure with this? Oct 19, 2023 · PWMコントロール機能付きファンとは. directly changing the DC voltage with which the fan is driven. Typically integrated into 4-pin fans, the additional pin is dedicated to PWM control. they only have 2 wires). I’ve never bothered to check a PWM’s frequency, but that acceptable range looks wide AF so it’ll probably be fine. Correct Thus PWM is more precise. Its duty cycle will control the fan's speed. 1. Jul 4, 2024 · If you’ve built a PC in the last few decades, you’ve almost certainly come across a 3-pin (or even 2-pin) DC fan or a 4-pin PWM fan (if not both) when setting up the cooling inside your case. 12v PWM 4-pin Computer Fan - I'm using 2 x 120mm Corsair fans. The PWM function is commonly used in OEM cases. For example, Variable-speed computer fan controllers usually use PWM, PWM fan is controlled with PWM signal, while non-PWM is controlled with voltage. The specs require a PWM signal with a frequency of 25 kHz (with tolerance, 21-28 kHz), but our usual analogWrite function doesn't output anywhere near that frequency. 早期的風扇只有兩根線，一般用紅線和黑線來表示，紅色表示電源正、黑線表示電源負，即只要接上合適的電壓，風扇就會轉動，而且是全速轉動，速度不可調。. Oct 9, 2021 · You may have some misunderstanding between fan's PWM frequency and speed control signal PWM frequency. 12v Power Adapter - 1A or 2A should be fine depending on your fan's current draw. I'm trying to use PWM on the gate to control the voltage supplied to the fan and in that way control the fan speed. May 20, 2025 · pwm対応のファンが使われるパーツは主に、空冷式cpuクーラーのファン、水冷式cpuクーラーのラジエータのファン、pcケースファンです。 CPUクーラーのファンは、CPUの温度と直結する部分なので、基本的に4ピンのPWM対応のものが使われることが多いです。 5. Fan speed as PWM duty cycle is being increased % of full speed The minimum fan speed specified is also the minimum fan starting speed. Feb 19, 2024 · The target PWM frequency for 4 pin computer fans is 25Khz. Apr 19, 2025 · These fans are also very compatible. Aug 14, 2019 · 1-電腦上的風扇 1 兩線式cpu風扇的工作原理. You can use Arduino's default PWM frequency, but if you don't want to hear a 3-pin fan, use >=20kHz or <=30Hz. 150 ohm resistor can be omitted but it’s there to protect the mosfet. The goal of such a circuit is to send a PWM control signal to a 4 wire PC fan, so that the fan can modulate it's speed (NOT to pulse the 12V supply). The use of PWM in computer fans offers several benefits, including: Silent Operation. The project involves rotary encoding, PWM control, PCB design, and C# application programming. This is much faster than the usual Arduino PWM frequency of around 600Hz. Figure 7 depicts the circuit used for high-frequency PWM. The PWM signal drives the Aug 21, 2011 · If it is a PWM fan, you'll need to change the Arduino's PWM frequency: Very few fans are built to accept a ~500Hz PWM signal. Application examples of PWM control fan (min-1) Here are a few application examples of PWM control fan. The I²C Bus is required to be set up in your configuration for this sensor to work. 12v DC Female Jack - with wire outlets Oct 1, 2017 · The warning about voltage supply to a 4-pin fan is based on two issues as I understand it. 10K is not needed on most of arduino boards, but it will ensure best mosfet operation. Apr 23, 2025 · PWM offers a sophisticated solution to this challenge, enhancing both efficiency and longevity by precisely controlling fan speed based on real-time temperature readings. But you could be hearing a whine if you PWM a fan in your hearing range. The expectation is a 4 wire PWM controlled fan when properly implemented will be significantly quieter than a similar 3 wire fan. The fan itself has a weak internal pullup on the PWM pin and the fan is just looking for the pin to be pulled to ground to toggle it. e. Benefits of PWM in Computer Fans. Jul 4, 2022 · I'm working on a project where I need to control the fan speed of a 3-pin 12V PC fan (Thermaltake Pure 20). \$\endgroup\$ – May 10, 2024 · The PWM process regulates the fan within the PC's CPU, which effectively disperses heat. PWM technology keeps LEDs from overheating while preserving their brightness. 5 (PWM) it seems like the frequency is based on this period T which is how quickly the hardware counts up from 0 to TOP. The currant involved in minimal. PWM fans are 4-pin fans where the fourth wire sends a PWM signal to the fan motor. facebook. May 12, 2011 · A bit of background: I'm looking to control PWM computer cooling fans directly from an ATTiny85, the fans want a ~15-25khz PWM signal. As specified by Intel (c. The fan is powered by a 12V power supply that goes through an n-channel MOSFET (IRF520) which I control with my Arduino Nano. The introduction of 4 wire PWM controlled fans is a means to reduce the overall system acoustics. Given Below are Advantages and Disadvantages of PWM : Advantages. The standard for PC PWM fans is 25kHz! ~30khz works fine too, and the Arduino can put that out. The fan RPM (as a percentage of Jul 10, 2008 · Hello, I've been trying to control a 4-pin computer fan using the arduino. “4-Wire Pulse Width Modulation (PWM) Controlled Fans”, Intel Corporation September 2005, revision 1. This brings together the best of both for awesome cooling. a PC fan draws some 400mA, so i could run 20-22 fans PWM stands for "Pulse Width Modulation," and it controls the fan speed by adjusting the frequency of current pulses. Basically a 4 - wire computer fan is to be controlled by a square wave PWM signal with fixed frequency of about 21 - 25 kHz, having a duty cycle from 25 to 100% (1/4 to full fan speed). At 25% (or less) the fan may stop (or not), depending on the manufacturer. One is that the fan also contains a printed circuit board with components to do several jobs like simulating a commutator and brush system for this brushless motor, generating a speed pulse output, and modulating the 12VDC supplied on Pin #2 with the PWM signal supplied on Pin #4 before sending that to Mar 31, 2025 · Consider a sample configuration: – CPU Temperature: 0°C – 42°C (Fan Speed 40%) – CPU Temperature: 42°C – 65°C (Fan Speed 70%) – CPU Temperature: 65°C and above (Fan Speed 100%) This configuration helps maintain adequate cooling without excessive noise during normal operation. Most new motherboards have 4-pin PWM slots. The recommended PWM frequency range for most 4-wire fans is about 15kHz to 30kHz, though some fans can go as low as 100Hz or as high as 100kHz. Advantages and Disadvantages of PWM . Low speed made the sound worse. Lower frequencies ( in 20 to 100Hz range ) result in fan being able to start and run slower ( with lower PWM duty cycles ) but they might "rattle". If it is a non-PWM fan, that's a different setup altogether. (1) This system controls the fan speed in response to changing device temperature. If the frequency of the PWM signal is too slow, the fan’s speed will noticeably oscillate within PWM cycle resulting in undesirable fan noise. This allows for more accurate fan speed control, which helps optimize both performance and noise reduction. What you want to do is put an 'accumulator' (an RC filter) between the PWM output and an analog input pin, and read the voltage off of that. Jun 28, 2023 · The "Noctua PWM Specifications White Paper" [1] and the "4-Wire Pulse Width Modulation (PWM) Controlled Fans" from Intel [2] mention that the PWM frequency should be about 25kHz. Jul 16, 2021 · PWM (Pulse Width Modulation) Function The PWM (Pulse Width Modulation) function is commonly used for controlling fan speed. You can even mix DC and PWM fans in one PC. PWM computer fans usually expect something like 25kHz for proper operation . I reckon that because it's what motor controllers in RC vehicles do. It is This just measures the PWM signal and then controls the motor accordingly. 3 Fan Speed Response to PWM Control Input Signal The PWM input shall be delivered to the fan through the control signal on Pin 4 (see Section 2. If I use " TCCR0B = TCCR0B & 0b11111101 | 0x01;" from the Arduino PWM frequency howto, I can get 1khz from pin0 and 2khz Jul 14, 2016 · Thats a very good Read !!!! So I currently have my EK ddc pwm wire plug’ed into CPU FAN 1 and my and Silverstone PWM fan hub controller plug’ed into CPU FAN OP ///// “ASUS Sabertooth tuff series R 2. No need for other circuits. § Mar 17, 2022 · Most 4-pin PWM fans require a signal with 25 kHz frequency, which should be within the capacity of most low-end microcontrollers. Also many fans only woek over x% and stand still on less power. It employs a digital signal with a variable duty cycle—the ratio of on-time to the total cycle—to regulate fan speed. It causes a buzzing The fan can be controlled either by a PWM signal or by outputing a DC voltage using its DAC. The main advantage is that power loss in the switching device is Modulation (PWM) control signal on the 4-wire fan interface. The control input is usually an open-drain or open-collector output with a 5 V or 3. In reading the RP2040 datasheet [3] section 4. Understanding CPU fan control modes also involves recognizing real-world scenarios where each method becomes more advantageous. As for controlling the fan’s speed, it’s a matter of writing the desired value into the PWM register. Example schematic for a single 12V fan: PWM control. （1） This system controls the fan speed in response to changing device temperature. Oct 7, 2018 · Say I have a bunch of 0. Feb 6, 2019 · However the PWM frequency is the maximum on time, at 50% you will have a square wave that is HIGH for 20 μS and low for 20 μS. Oct 15, 2014 · SAS is correct - lowering the PWM to 31Hz works great. Mar 13, 2025 · This method is less common in modern fans, as it can be less efficient and less accurate than PWM control. RPM Fan speed as PWM duty cycle is being reduced PWM Duty cycle Example Min. However, the control signal PWM frequency, which user send to fan to control the fan speed is *NOT* used directly for Speed vs. Cost $7 . The frequency at which the power is turned on and off is way too quick for humans to tell the difference, so we don’t see the fan going on and off. The circuit looks like this: May 3, 2022 · Use of an ESP8266 to PWM control a 12Vdc, 2-wire computer fan, with a MOSFET (first with Tasmota, then a change to using ESPHome) Goals. 3 V pull-up. By combining a PWM control circuit and thermistor that detects temperature of device and its parts, it is able to control the fan speed of PWM control fan in response to the changing temperature. 4). Cost $8-$15 USD. They have to all work to the same spec otherwise certain motherboards would require certain fans. 30Hz can still give a 'knockin' sound. They are perfect for both enthusiasts and casual users. The voltage never changes, however, by turning the power off and on, we can modulate (adjust) the speed of the fan. By combining a PWM control circuit and thermistor that detects temperature of device and its parts, it is able to control the fan speed of PWM control Delta Pulse Width Modulation PWM fans offer full lineup of speed control. The frequency can be also too high. As loose The PWM switching frequency can vary greatly depending on load and application. I now drive them using the above PWM circuit to vary their speed. Aug 9, 2020 · A high frequency PWM controller usually operates above the 20KHz, thus the human ear cannot hear this sound. The default PWM frequency from a Pro-Mini is well below that, and within the human hearing range of 20Hz — 20Khz. 3：Automatic mode. You need to use simple cheap fans with only power to have them work. htigw cleuj fvhnr jmxat sgaau jov qvh nbht rotj vudwhih