Fan control circuit and system

US20140186156A1Inactive Publication Date: 2014-07-03ANPEC ELECTRONICS CORPORATION

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[0018]Please refer to FIG. 2, which is a schematic diagram of a fan control system 20 according to an embodiment of the present invention. As shown in FIG. 2, the fan control system 20 includes a two-wire fan 202, a DC voltage source 204, a temperature sensor 206, an external control module 208 and a fan control circuit 250. The fan control circuit 250 includes a modulation converting module 210, a selection device 212, a DC-DC converter 214, a rotational speed detecting module 216, a rotational speed converting module 218 and a signal integrating device 220. The power pin of the two-wire fan 202 is coupled to the DC-DC converter 214, and the DC-DC converter 214 supplies an input voltage Vin′, where magnitude of the input voltage Vin′ determines rotational speed of the two-wire fan 202. Since the DC-DC converter 214 provides flexibility for voltage conversion between the input and output voltages, a voltage VCC provided by the DC voltage source 204 is only required to be within a sp...

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Abstract

A fan control circuit for controlling a two-wire or three wire fan in a fan control system includes: a rotational speed detecting module, for detecting a rotational speed of the fan, in order to generate a rotational speed signal; a rotational speed converting module, coupled to the rotational speed detecting module, for converting the rotational speed signal into a first voltage signal; and a feedback control module, coupled to the rotational speed converting module, for generating a fan control signal to control the fan according to the first voltage signal.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a fan control circuit and system, and more particularly, to a fan control circuit and a related fan control system for controlling a two-wire or three-wire fan, wherein the fan control circuit and the fan control system are capable of controlling a rotational speed of the fan by detecting the rotational speed and integrating an external control signal using a signal integrating device.[0003]2. Description of the Prior Art[0004]Fans are widely applied in computer systems for heat dissipation. A fan can be divided into three types: four-wire, three-wire and two-wire. The four-wire fan has four pins: power, ground, tachometer and pulse width modulation (PWM) input, where the power pin is for providing power for the fan to operate, the tachometer pin is for detecting rotational speed information of the fan, and the PWM input pin controls rotational speed of the fan via a PWM signal. The thre...

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Application Information

Patent Timeline

03 Jul 2014

Publication

US20140186156A1

IPC: F04D27/00

CPC: F04D27/004; Y02B30/70

Inventors: LAI, CHING-FENG; LIU, DONG-YI