An electronic device is provided. When the electronic device is at a power exhaustion state and a first external device with a charging function is coupled to a connection interface to provide a first supply voltage to a power pin of the connection interface, a voltage regulation unit transforms the first supply voltage to a first operation voltage, and a storage unit powered by the first operation voltage outputs device information of the electronic device to the first external device through a signal transmitting/receiving pin set of the connection interface. When the first external device provides a second supply voltage to the power pin in response to the device information, the electronic device enters a charging mode. In the charging mode, the charging unit provides a charging voltage according to the second supply voltage to charge the battery unit and provides a second operation voltage to a processing unit.