| 摘要 |
PROBLEM TO BE SOLVED: To use the battery pack of a portable telephone in which a sufficient capacity remains for another portable telephone whose battery pack does not have a capacity any more, by selecting a charging circuit when a battery pack is charged, and selecting a booster circuit when a battery pack of another portable telephone is charged. SOLUTION: Connecting a battery pack to one of a charging circuit 2 and a booster circuit 3 through a charging power changeover switch 6, the charging circuit 2 charges the battery pack 1, and the booster circuit 3 boosts the voltage of the battery pack 1 to a voltage capable of charging a battery pack to be used for another portable telephone. To the other of the charging circuit 2 and the booster circuit 3, an external input/output(I/O) connector 4 is connected through a charging power changeover switch 5, and charging power is supplied to an external portable telephone. A charging power control circuit 7 controls charging power changeover switches 5, 6. Consequently, use for supplying charging power from outside or to an external portable telephone becomes feasible. |
