Patent ID: 8456122
Filing Date: 2013-06-04
Classification: G01R,G05D,G06F,H05K,Y02D

Abstract:
1. A control circuit comprising: a current sensing circuit to sense current supplied for an electronic device by a power supply, and output a first voltage signal; an amplifying circuit; an analog to digital converter (ADC), wherein the amplifying circuit is connected between the current sensing circuit and the ADC to amplify the first voltage signal output from the current sensing circuit to a second voltage signal, the ADC converts the second voltage signal to a digital signal; a processor to output pulse width modulation (PWM) signals according to the digital signal; and a switching circuit connected between the processor and a fan to control the fan of the electronic device according to the PWM signals; wherein the switching circuit comprises a field effect transistor (FET) and a bipolar junction transistor (BJT) transistor, a gate of the FET is connected to the processor through a first resistor, a source of the FET is grounded, a drain of the FET is connected to the power supply through a second resistor, the drain of the FET is further connected to a base of the BJT transistor through a third resistor, an emitter of the BJT transistor is connected to the power supply, a collector of the BJT transistor is connected to the fan.