https://knightli.com/en/tags/fan-connector-pinout/ Recent content in Fan-Connector-Pinout on KnightLi Blog Hugo -- gohugo.io en Tue, 06 May 2025 00:00:00 +0000 https://knightli.com/en/2025/05/06/pwm-fan-dc-fan-interface-and-control/ Tue, 06 May 2025 00:00:00 +0000 https://knightli.com/en/2025/05/06/pwm-fan-dc-fan-interface-and-control/ <h2 id="pin-definitions">Pin Definitions </h2><ul> <li>Fan connector basics<br> Typical cooling fans use 3-pin or 4-pin connectors (common 2510 form factor).<br> A 4-pin fan can usually be connected to a 3-pin header with alignment.</li> </ul> <p><img src="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/1.png" width="361" height="489" srcset="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/1_hu_cb6598f08d81425a.png 480w, https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/1_hu_40bd393eea2784e5.png 1024w" loading="lazy" class="gallery-image" data-flex-grow="73" data-flex-basis="177px" ></p> <ul> <li> <p>4-pin fan connector<br> <img src="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/2.png" width="347" height="597" srcset="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/2_hu_7b5cd10916131315.png 480w, https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/2_hu_bebeeeae615f720a.png 1024w" loading="lazy" class="gallery-image" data-flex-grow="58" data-flex-basis="139px" ></p> </li> <li> <p>3-pin fan connector<br> <img src="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/3.png" width="311" height="341" srcset="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/3_hu_7e75f7c9c82c93f7.png 480w, https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/3_hu_2f76c3b465e21cd.png 1024w" loading="lazy" class="gallery-image" data-flex-grow="91" data-flex-basis="218px" ></p> </li> </ul> <h2 id="fg--tach-signal">FG / TACH Signal </h2><p><code>TACH</code> / <code>FG</code> is the fan speed feedback signal, usually output as pulses.</p> <p>The motherboard estimates real-time RPM by counting FG pulses. The pulse count per revolution depends on fan design (for example 2 pulses/rev or 3 pulses/rev).</p> <p>A common formula is:</p> <ul> <li>If pulses per revolution = 2, then <code>RPM = FG frequency * 30</code></li> <li>If pulses per revolution = 3, then <code>RPM = FG frequency * 20</code></li> </ul> <h2 id="dc-speed-control">DC Speed Control </h2><p>DC fan speed control is achieved by changing supply voltage.</p> <h2 id="pwm-speed-control">PWM Speed Control </h2><h3 id="pwm-duty-cycle">PWM Duty Cycle </h3><p><img src="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/4.png" width="1867" height="651" srcset="https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/4_hu_9abb7044887388d6.png 480w, https://knightli.com/2025/05/06/pwm%E8%B0%83%E9%80%9F-dc%E8%B0%83%E9%80%9F-%E9%A3%8E%E6%89%87-%E6%8E%A5%E5%8F%A3%E5%AE%9A%E4%B9%89/4_hu_da6b57b833752ee.png 1024w" loading="lazy" class="gallery-image" data-flex-grow="286" data-flex-basis="688px" ></p> <p>Duty cycle <code>D</code> is the ratio of high-level time <code>t_on</code> to period <code>T</code>.</p> <p>PWM fan control adjusts speed by changing duty cycle:</p> <ul> <li>100% duty: full speed</li> <li>50% duty: roughly medium speed</li> <li>0% duty: stop</li> </ul> <h3 id="pwm-frequency">PWM Frequency </h3><p>PWM frequency is the switching frequency of the PWM signal (in Hz).</p> <p>Common practical ranges:</p> <ul> <li>Low frequency: 1 kHz to 5 kHz (still usable on some older controllers)</li> <li>Typical range: 20 kHz to 30 kHz (common for many motherboards/fans)</li> <li>Higher frequency: &gt;30 kHz (used in some designs, with different noise/efficiency trade-offs)</li> </ul> <h3 id="pwm-voltage-level">PWM Voltage Level </h3><p>PWM amplitude is the voltage difference between high and low levels. Common logic levels are 3.3V or 5V, depending on fan/controller design.<br> Always verify the fan&rsquo;s electrical requirements in the datasheet before final design.</p>