Patent ID: 8122267

Claim:
A power control circuit for a hard disk drive (HDD), the circuit comprising: a first connector connected to a power supply, comprising a first power input pin receiving a first voltage signal from the power supply, and a second power input pin receiving a second voltage signal from the power supply; a second connector connected to the HDD, the second connector comprising a detection pin outputting a detection signal, a first power output pin outputting the first voltage signal to the HDD, and a second power output pin outputting the second voltage signal to the HDD; and a first control circuit, comprising: a first electric switch comprising a control terminal connected to the detection pin of the second connector receiving the detection signal and connected to the second power input pin of the first connector via a first resistor, a power terminal connected to the second power input pin of the first connector via a second resistor, and a ground terminal; a second electric switch comprising a control terminal connected to the power terminal of the first electric switch, a power terminal connected to the first power input pin of the first connector via a third resistor, and a ground terminal; a third electric switch comprising a control terminal connected to the power terminal of the second electric switch, an input terminal connected to the first power input pin of the first connector, and an output terminal connected to the first power output pin of the second connector; and a fourth electric switch comprising a control terminal connected to the output terminal of the third electric switch via a fourth resistor, an input terminal connected to the second power input pin of the first connector, and an output terminal connected to the second power output pin of the second connector; wherein in response to the HDD being properly connected to the second connector, the detection pin outputs the detection signal at a low level to turn off the first electric switch, therefore, the second, third, and fourth electric switches are turned on, the first and second voltage signals are transmitted to the HDD via the third and fourth electric switches and the second connector.