Abstract: An apparatus for supplying power to a controller has a main power switch provided on a power supply path of a main power to a controller, a sub power switch provided on a power supply path of a sub power to the controller, and a power supply controller that opens the main power switch and closes the sub power switch so that the sub power is supplied to the controller when not receiving the main power. Accordingly, the power supply to the controller can be more stably switched. Additionally, an over-discharged battery is not used in power supply, and the controller can have a more stable reset operation.

Abstract: A portable electronic device having a body having a first contact protrusion and a second contact protrusion at a side for receiving an external power supply, and a third contact protrusion for receiving a power status, and a battery device having a first contact terminal, a second contact terminal and a third contact terminal for connecting with the first to third contact protrusions of the body to provide the body with the power supply and the power status. The battery device has the first and the second contact terminals which are longer than the third contact terminal in a first direction and a second direction by a predetermined distance, respectively, to maintain the first and second contact terminals in contact with the respective contact protrusions longer than the third contact terminal.