مخطط الأطراف

مخطط أطراف موصل مروحة الحاسوب (4 أطراف PWM، Intel بـ 4 أسلاك)

افتح مخطط الأطراف التفاعلي

الأطراف

• 1: GND (black) — fan ground and the return path for the tach signal
• 2: +12V (yellow) — sits at full 12V on a 4-pin header; the fan regulates its own speed from the PWM line, so never try to slow a 4-wire fan by lowering this rail
• 3: TACH / SENSE (green) — open-collector output from the fan, 2 pulses per revolution, so RPM = pulses per second × 30. It needs a pull-up to 5V or 3.3V (the motherboard has one, an MCU does not) and it only pulls low, so it will never over-volt a 3.3V input through a 3.3V pull-up
• 4: PWM CONTROL (blue) — 25kHz control input (21–28kHz per spec), 5V logic, pulled up inside the fan and rated to sink about 5mA, so drive it open-drain from a 3.3V MCU rather than pushing 3.3V high. A 3-pin fan simply has no pin 4: it plugs onto pins 1–3 of the same header (the plug is keyed and offset) and is then speed-controlled by varying its 12V rail in DC mode instead. Conversely a 4-pin fan on a 3-pin header runs flat out, because its PWM line floats to its internal pull-up

المواصفات

الملاحظات

• أمسك قابس المروحة ونوافذه المعدنية نحوك والأسلاك للأسفل: الطرف 1 (أسود، GND) على اليسار. على موصل اللوحة الأم، منظوراً من الأعلى ولسانه البلاستيكي في الخلف، تُقرأ نفس الأطراف 4-3-2-1 من اليسار إلى اليمين.