1. Field
An embodiment of the present invention relates to an external battery.
2. Description of the Related Art
Recent electronic appliances, for example, a palmtop computer, a mobile phone, PDA, etc., are developed for portable use. These portable electronic appliances may be supplied with the electric power required for their use from a battery. The recent portable electronic appliances have their own functions, and additional functions are gradually added to diversify the functions of the portable electronic appliance, such that even a single portable electronic appliance performs various functions. Thus, the amount of electric power necessary to use the portable electronic appliance is gradually increasing, and a primary battery with a large capacity may be used.
Furthermore, an external battery, which is not attached to the portable electronic appliance, but is instead carried separately, is developed.
FIG. 1 is a block diagram schematically illustrating a configuration of an existing external battery. Referring to FIG. 1, an input end (e.g., input terminal(s)) 31 of an external battery 30 is fed with external electric power from a charger 10. A main controller unit (MCU) 32 senses a voltage at the input end 31 to detect a type of the charger 10, and to control an output current of a charger integrated circuit (charger IC) 33, and the charger IC 33 feeds electric current to a battery 34. In addition, the MCU 32 senses a voltage of the battery 34, and displays the sensed voltage on a display unit 37. The voltage outputted from the battery 34 is boosted by a DC-DC converter 35, and is fed to an external device 20 via an output end (e.g., output terminal(s)) 36 of the external battery 30.
A rechargeable secondary battery may be employed as the battery 34 mounted in the external battery 30. This secondary battery 34 is made by electrically coupling a bare cell 34a, which includes a can that is sealed and accommodates an electrode assembly and electrolyte, to a protection circuit module (PCM circuit) 34b. The PCM circuit 34b protects the bare cell 34a by preventing overcharging (e.g., overcharge voltage) that may otherwise occur when recharging the bare cell 34a. 
In the external battery 30, the PCM circuit 34b senses the voltage of the battery 34 to prevent overcharging/over-recharging, and to control the current used to charge the battery, while the MCU 32 also senses the voltage of the battery 34 to enable the display of a capacity (e.g., a remaining energy capacity) of the battery, thereby duplicating the sensing of the voltage of the battery 34.