Patent ID: 8520350

Claim:
A protection circuit is connected between a central processing unit (CPU) socket and a digital integrated chip, to prevent the digital integrated chip from being damaged when a CPU is mounted in the CPU socket, wherein the CPU socket comprising a signal pin, the protection circuit comprising: first to fourth resistors; a first electronic switch comprising first to third terminals, wherein the first terminal of the first electronic switch is connected to the signal pin of the CPU socket, connected to a first power source through the first resistor, and grounded through the second resistor, the second terminal of the first electronic switch is grounded, the third terminal of the first electronic switch is connected to a second power source through the third resistor; and a second electronic switch comprising first to third terminals, the first terminal of the second electronic switch is connected to the third terminal of the first electronic switch through the fourth resistor, the second terminal of the second electronic switch is connected to the digital integrated chip, the third terminal of the second electronic switch is connected to a data transmitting line of a system management bus (SMBus); wherein when the CPU socket does not contain a CPU, the signal pin of the CPU socket outputs a high level signal, the first and second electronic switches are turned on, the data transmitting line of the SMBus is connected to the digital integrated chip, the working parameters of the digital integrated chip can be regulated, when the CPU socket contains the CPU, the signal pin of the CPU socket outputs a low level signal, the first and second electronic switches are turned off, the data transmitting line of the SMBus is disconnected from the digital integrated chip, to prevent damage to the digital integrated chip.