Patent ID: 9335806
Filing Date: 2016-05-10
CPC Classification: G06F

Claim Text:
1. A power supply circuit applicable to a central processing unit (CPU) of a computer, the power supply circuit comprising: a pulse width modulation (PWM) controller comprising a first output terminal and a second output terminal; a first power circuit connected to the first output terminal of the PWM controller and the CPU; a second power circuit connected to the second output terminal of the PWM controller and the CPU, the second power circuit comprising an inductor; a comparing circuit comprising first and second resistors, and a comparator, wherein a non-inverting input terminal of the comparator is connected to a power source through the first resistor, the non-inverting input terminal of the comparator is grounded through the second resistor, an inverting input terminal of the comparator is connected to a reference power source, a power terminal of the comparator is connected to the power source, a ground terminal of comparator is grounded, the first resistor is a negative temperature coefficient thermistor and located near the inductor in the second power circuit; a first switch circuit connected to an output terminal of the comparator and the PWM controller; a second switch circuit connected to the PWM controller; a third switch circuit connected to the output terminal of the comparator and the second switch circuit; a first compensation circuit connected to the first switch circuit; and a second compensation circuit connected to the second switch circuit; wherein when the computer operates normally, the first and second power circuits operate, the comparing circuit outputs a first control signal to the first and third switch circuits according to the voltage of the non-inverting input terminal, the first and third switch circuits are turned on, the second switch circuit is turned off, the first compensation circuit outputs a first compensation signal to the PWM controller through the first switch circuit, the PWM controller regulates duty cycle of pulse signals and outputs the regulated pulse signals to the first and second power circuits, to provide a stable voltage to the CPU; when the computer is powered off, the first power circuit operates and the second power circuit does not operate, the comparing circuit outputs a second control signal to the first and third switch circuits according to the voltage of the non-inverting input terminal, the first and third switch circuits are turned off, the second switch circuit is turned on, the second compensation circuit outputs a second compensation signal to the PWM controller through the second switch circuit, the PWM controller regulates duty cycle of a pulse signal and outputs the regulated pulse signal to the first power circuit, to provide a stable voltage to the CPU.