Intel 4-Wire Pulse Width Modulation (PWM) Controlled Fans\u200b document.<\/a>\n<\/p>\n\nTachometer Output Signal
\n<\/h5>\n
\nOpen-collector or open-drain type output\n<\/p>\n
\nMotherboard may have to pull up or it may happen to 12V in fan (there is no rule it seems and there will be exceptions to what is considered "normal").\n<\/p>\n
\nThe tachometer output typically comes from a Hall-effect sensor mounted on the motor driver PCB on the fan frame. One or more magnets embedded in the fan rotor hub activate the Hall-effect sensor as they pass by. Fans that typically use an open drain\/open collector output.\n<\/p>\n
\nPWM Control Input Signal
\n<\/h5>\n
\nBase frequency is 25kHz with acceptable range from 21kHz to 28kHz.\n<\/p>\n
\nInput has TTL level and includes pull-up resistor to 5V or to 3.3V in new constructions, but could be pulled up to 12V\n<\/p>\n
\nSignal is not inverted and 100% PWM means maximal revolutions of fan. Motherboard has open-collector type output.\n<\/p>\n
\nIf left floating fan runs at full speed.\n<\/p>\n
\nIt actually turns out this pin needs a pull up for some fans we've come across, even though the Intel spec document above doesn't specify this (it specifies an open collector output). The safest solution we've found is to add a pull up resistor to +5V as although some fans are fine with this pin pulled to +12V the Intel spec specifies max 5.25V on this pin.\n<\/p>\n
\n3 Pin Fan
\n<\/h4>\n
\nCan be the same connector with a 3 pin socket plugged into it (pin 4 missing), or a 3 pin version of the header, into which a 4 pin fan can be connected with pin 4 floating causing the fan to run at full speed.\n<\/p>\n
\n3 pin Molex KK connec\u200btor:\n<\/p>\n
\nLine connector Molex 22-01-3037
\nLine connector contacts Molex 08-50-0114
\nPCB header Molex 22-23-2031, Farnell 1462950\n<\/p>\n
\n <\/p>\n","protected":false},"excerpt":{"rendered":"
There is no agreed standard connector for PC fans, but there is a most choice. 4 Pin Fan Molex have a special 4 pin fan connector which is designed to accept both 3 pin (no PWM speed control) and 4 pin fans. Line connector Molex 47054-1000, RS 720-5990 Line connector contacts Molex 47054-1000, RS 172-9178 PCB […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62],"tags":[],"class_list":["post-1458","post","type-post","status-publish","format-standard","hentry","category-pc"],"_links":{"self":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1458","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/comments?post=1458"}],"version-history":[{"count":10,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1458\/revisions"}],"predecessor-version":[{"id":1985,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1458\/revisions\/1985"}],"wp:attachment":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/media?parent=1458"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/categories?post=1458"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/tags?post=1458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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