A portable electronic device includes a connector including first and second data pins and a power pin; a battery charging circuit configured to receive a charging current and a power voltage from an external device via the power pin and charge a battery according to the charging current; and a processor configured to make the first and second data pins, which are shorted by the external device, open and obtain an identification code via the first and second data pins from the external device after the first and second data pins are opened, wherein if the identification code matches a specific code, the processor sends a requirement to the external device, and the power voltage and the charging current received by the battery charging circuit are increased by the external device in response to the requirement.