Patent ID: 7880629

Claim:
A power supply device for supplying power to a communication device, comprising: a power source comprising a first negative pole, a second negative pole, and a positive pole; a first fuse connected to the first negative pole; a second fuse connected to the second negative pole; a voltage converter connected between the first fuse, the second fuse, and the communication device, configured for receiving first power signals from the power source via the first fuse and the second fuse, and converting the first power signals to second power signals, wherein the second power signals provide sufficient power for operating the communication device; a first resistor, a first end of the first resistor being connected to a joint of the first fuse and the voltage converter; a second resistor, a first end of the second resistor being connected to a joint of the second fuse and the voltage converter, a second end of the second resistor being connected to a second end of the first resistor; a third resistor, a first end of the third resistor being connected to a joint of the first resistor and the second resistor, a second end of the third resistor being connected to the positive pole of the power source; a photo coupler connected in parallel to the third resistor, configured for outputting a first electrical signal upon the condition that the first fuse and the second fuse are operational, and outputting a second electrical signal upon the condition that at least one of the first fuse and the second fuse are blown; and a central processing unit (CPU) connected to the photo coupler, configured for generating an alarm message upon receiving the second electrical signal from the photo coupler.