To provide a device and a method for controlling the rotational speed of a fan that achieve reduction in power consumption, suppression of noise due to switching, and reduction in electromagnetic interference, while having excellent heat-dissipation effects.
A controller for fan rotational speed 3 is provided with a controller 31, which detects the rotational-speed signal Sf of the fan 5, generates a first driving signal S1, when the rotational-speed signal Sf is higher than a preset rotational-speed signal Sref, and generates the first drive signal S1 and a second drive signal S2, when the rotational-speed signal Sf is lower than the preset rotational-speed signal Sref; a switch 32 electrically connected to the controller 31 so as to receive the first drive signal S1; and a voltage regulator 33 which is electrically connected to the controller 31, a switch 32, and a fan 5 that control the rotational speed of the fan 5, on the basis of the first/second driving signals S1, S2, while receiving the second drive signal S2.
TSAI MIN-SHI
HUANG WEN-HSI
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