Patent ID: 7177124

Claim:
A brushless DC fan motor driving circuit, comprising a control unit, a Hall element, a circuit for reverse protection and voltage drop, a transistor amplifier circuit, a magnetic noise elimination and protection circuit, a temperature sensor with negative temperature coefficient (NTC), and a control circuit, wherein said Hall element, said circuit for reverse protection and voltage drop, said transistor amplifier circuit, said magnetic noise elimination and protection circuit, said temperature sensor, and said control circuit are connected with said control unit; wherein said control unit comprises a plurality of pins; wherein said Hall element is to detect the position of the rotor of a motor and to acquire the running status of said motor; wherein said circuit for reverse protection and voltage drop is to keep the voltage of said control unit in an acceptable range in case of reverse voltage feedback or wrongly plugged connector and to prevent said control unit from damage; wherein said transistor amplifier circuit is to amplify the power output from said control unit; wherein said magnetic noise elimination and protection circuit is to avoid the counter-electromotive force (CEMF) of said motor so that voltage is kept on a certain degree by restraining said CEMF and the magnetic noise made by said motor is absorbed; wherein said temperature sensor with negative temperature coefficient and said control unit are for sensing temperature and, by comparing voltage burdens, when said temperature is getting higher, resolving speed is increased; wherein a third pin (CT) of said control unit is connected with a first capacitor and is grounded through said first capacitor, and is connected with a third pin (GND) of said Hall element, and said third pin (GND) of said Hall element is grounded; and wherein said third pin (CT) of said control unit is a CT pin and said third pin (GND) of said Hall element is a ground pin.