DC cooling fan which output signal

　　There are a lot of signal line DC cooling fan equipment above, below, we introduced by some of the output signal in the DC cooling fan.

　　Fan cooling fan equipment each size can match or RD FG signal line. Cooling fan has two lines, three lines, four lines. Two lines just positive and negative, in addition to the positive and negative poles three signal lines than another, and the signal line, there are two: one is the FG, which is the speed signal is a square wave signal, usually the signal frequency quadrupole fan * 30 = actual speed of the fan, there will be slow to say the actual speed. Another is the RD signal, its function is to operate the fan output is low, the fan does not turn the output high, CPU by detecting this signal to know the fans are running. Fan

　　Four-wire cooling fan, and in addition to the positive and negative FG, another typically PWM line, from the line input PWM signal duty cycle to adjust the fan speed, the rotational speed and the duty cycle change is substantially linear, generally in end did not change significantly. The curve changes with the internal circuit design of the cooling fan can be adjusted to achieve a different range.