Fan control system

Abstract

A fan control system for a fan on a motherboard includes an I/O controller installed on the motherboard and a control circuit electrically connected to the I/O controller. The fan includes a motor and a rotation speed detecting chip. The I/O controller outputs a rotation speed control signal and a pulse width modulation (PWM) signal. The rotation speed detecting chip detects a rotation speed of the fan, and outputs a rotation speed feedback signal according to the rotation speed of the fan. The I/O controller receives the rotation speed feedback signal, and adjusts a duty cycle of the PWM signal accordingly to change the rotation speed of the fan. The control circuit receives the rotation speed control signal, and outputs a fan driving signal accordingly. The motor receives the fan driving signal, and drives the fan to rotate in a direction according to the fan driving signal.

What is claimed is:  
     
         1 . A fan controlling system comprising:
 an I/O controller adapted to output a rotation speed control signal and a pulse width modulation (PWM) signal; and   a fan comprises a motor and a rotation speed detecting chip; wherein the rotation speed detecting chip detects a rotation speed of the fan, and outputs a rotation speed feedback signal according to the rotation speed of the fan; the I/O controller receives the rotation speed feedback signal, and adjusts a duty cycle of the PWM signal accordingly to change the rotation speed of the fan;   a control circuit electrically connected to the I/O controller; wherein the control circuit receives the rotation speed control signal, and outputs a fan driving signal accordingly; the motor receives the fan driving signal, and drives the fan to rotate in a direction according to the fan driving signal.   
     
     
         2 . The fan controlling system of  claim 1 , wherein the I/O controller comprises a first control signal output terminal; the control circuit comprises a first transistor, a first resistor, a second resistor, and a first MOSFET; the motor comprises a first input terminal; the first control signal output terminal receives a first DC voltage via the first resistor; the first control signal output terminal is electrically connected to a base of the first transistor; an emitter of the first transistor is grounded; a collector of the first transistor is electrically connected to a gate of the first MOSFET; the collector of the first transistor receives a second DC voltage via the second resistor; a drain of the first MOSFET receives the second DC voltage; and a source of the first MOSFET is electrically connected to the first input terminal. 
     
     
         3 . The fan controlling system of  claim 2 , wherein the I/O controller further comprises a fourth control signal output terminal; the control circuit further comprises a second transistor, a third resistor, a fourth resistor, a fifth resistor, and a second MOSFET; the motor further comprises a second input terminal; the fourth control signal output terminal receives the first DC voltage via the third resistor; the fourth control signal output terminal is electrically connected to a base of the second transistor; an emitter of the second transistor is grounded; a collector of the second transistor is electrically connected to a gate of the second MOSFET; the collector of the second transistor receives the second DC voltage via the fourth resistor; a drain of the second MOSFET is electrically connected to the second input terminal; and a source of the second MOSFET is grounded via the fifth resistor. 
     
     
         4 . The fan controlling system of  claim 3 , wherein the I/O controller further comprises a second control signal output terminal; the control circuit further comprises a third transistor, a sixth resistor, a seventh resistor, and a third MOSFET; the second control signal output terminal receives the first DC voltage via the sixth resistor; the second control signal output terminal is electrically connected to a base of the third transistor; an emitter of the third transistor is grounded; a collector of the third transistor is electrically connected to a gate of the third MOSFET; the collector of the third transistor receives the second DC voltage via the seventh resistor; a drain of the third MOSFET receives the second DC voltage; and a source of the third MOSFET is electrically connected to the drain of the second MOSFET. 
     
     
         5 . The fan controlling system of  claim 4 , wherein the I/O controller further comprises a third control signal output terminal; the control circuit further comprises a fourth transistor, a eighth resistor, a ninth resistor, and a fourth MOSFET; the third control signal output terminal receives the first DC voltage via the eighth resistor; the third control signal output terminal is electrically connected to a base of the fourth transistor; an emitter of the fourth transistor is grounded; a collector of the fourth transistor is electrically connected to a gate of the fourth MOSFET; the collector of the fourth transistor receives the second DC voltage via the ninth resistor; a drain of the fourth MOSFET is electrically connected to the source of the first MOSFET; and a source of the fourth MOSFET is electrically connected to the source of the second MOSFET and the fifth resistor. 
     
     
         6 . The fan controlling system of  claim 1 , wherein the I/O controller further comprises a feedback signal input terminal; the rotation speed detecting chip comprises a rotation speed signal output terminal; and the rotation speed signal output terminal is electrically connected to the feedback signal input terminal to output the rotation speed feedback signal. 
     
     
         7 . The fan controlling system of  claim 3 , wherein the I/O controller further comprises a current signal input terminal; and the current signal input terminal is electrically connected to the source of the second MOSFET and the fifth resistor to collect current signals flowing through the fan. 
     
     
         8 . The fan controlling system of  claim 5 , wherein the first DC voltage is a +3V standby voltage; the second DC voltage is a +12V voltage; the first transistor, the second transistor, the third transistor, and the fourth transistor are NPN type transistors; and the first MOSFET, the second MOSFET, the third MOSFET, and the fourth MOSFET are N-channel MOSFETs. 
     
     
         9 . A fan controlling system for a fan on a motherboard comprising:
 an I/O controller adapted to be installed on the motherboard; wherein the I/O controller outputs a rotation speed control signal and a pulse width modulation (PWM) signal; and   a control circuit electrically connected to the I/O controller; wherein the fan comprises a motor and a rotation speed detecting chip; the rotation speed detecting chip detects a rotation speed of the fan, and outputs a rotation speed feedback signal according to the rotation speed of the fan; the I/O controller receives the rotation speed feedback signal, and adjusts a duty cycle of the PWM signal accordingly to change the rotation speed of the fan; the control circuit receives the rotation speed control signal, and outputs a fan driving signal accordingly; the motor receives the fan driving signal, and drives the fan to rotate in a direction according to the fan driving signal.   
     
     
         10 . The fan controlling system of  claim 9 , wherein the I/O controller comprises a first control signal output terminal; the control circuit comprises a first transistor, a first resistor, a second resistor, and a first MOSFET; the motor comprises a first input terminal; the first control signal output terminal receives a first DC voltage via the first resistor; the first control signal output terminal is electrically connected to a base of the first transistor; an emitter of the first transistor is grounded; a collector of the first transistor is electrically connected to a gate of the first MOSFET; the collector of the first transistor receives a second DC voltage via the second resistor; a drain of the first MOSFET receives the second DC voltage; and a source of the first MOSFET is electrically connected to the first input terminal. 
     
     
         11 . The fan controlling system of  claim 10 , wherein the I/O controller further comprises a fourth control signal output terminal; the control circuit further comprises a second transistor, a third resistor, a fourth resistor, a fifth resistor, and a second MOSFET; the motor further comprises a second input terminal; the fourth control signal output terminal receives the first DC voltage via the third resistor; the fourth control signal output terminal is electrically connected to a base of the second transistor; an emitter of the second transistor is grounded; a collector of the second transistor is electrically connected to a gate of the second MOSFET; the collector of the second transistor receives the second DC voltage via the fourth resistor; a drain of the second MOSFET is electrically connected to the second input terminal; and a source of the second MOSFET is grounded via the fifth resistor. 
     
     
         12 . The fan controlling system of  claim 11 , wherein the I/O controller further comprises a second control signal output terminal; the control circuit further comprises a third transistor, a sixth resistor, a seventh resistor, and a third MOSFET; the second control signal output terminal receives the first DC voltage via the sixth resistor; the second control signal output terminal is electrically connected to a base of the third transistor; an emitter of the third transistor is grounded; a collector of the third transistor is electrically connected to a gate of the third MOSFET; the collector of the third transistor receives the second DC voltage via the seventh resistor; a drain of the third MOSFET receives the second DC voltage; and a source of the third MOSFET is electrically connected to the drain of the second MOSFET. 
     
     
         13 . The fan controlling system of  claim 12 , wherein the I/O controller further comprises a third control signal output terminal; the control circuit further comprises a fourth transistor, a eighth resistor, a ninth resistor, and a fourth MOSFET; the third control signal output terminal receives the first DC voltage via the eighth resistor; the third control signal output terminal is electrically connected to a base of the fourth transistor; an emitter of the fourth transistor is grounded; a collector of the fourth transistor is electrically connected to a gate of the fourth MOSFET; the collector of the fourth transistor receives the second DC voltage via the ninth resistor; a drain of the fourth MOSFET is electrically connected to the source of the first MOSFET; and a source of the fourth MOSFET is electrically connected to the source of the second MOSFET and the fifth resistor. 
     
     
         14 . The fan controlling system of  claim 9 , wherein the I/O controller further comprises a feedback signal input terminal; the rotation speed detecting chip comprises a rotation speed signal output terminal; and the rotation speed signal output terminal is electrically connected to the feedback signal input terminal to output the rotation speed feedback signal. 
     
     
         15 . The fan controlling system of  claim 11 , wherein the I/O controller further comprises a current signal input terminal; and the current signal input terminal is electrically connected to the source of the second MOSFET and the fifth resistor to collect current signals flowing through the fan. 
     
     
         16 . The fan controlling system of  claim 13 , wherein the first DC voltage is a +3V standby voltage; the second DC voltage is a +12V voltage; the first transistor, the second transistor, the third transistor, and the fourth transistor are NPN type transistors; and the first MOSFET, the second MOSFET, the third MOSFET, and the fourth MOSFET are N-channel MOSFETs.