| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a portable telephone wherein charging operation can be properly detected, load of overcharging of a battery is reduced, power consumption by the battery is eliminated, and communication is sustainable. <P>SOLUTION: At start of charging, a charge control circuit 12 changes the setting of a switch 15 to the constant current source side, and carries out charging with a constant current. If increase in battery voltage from V0 (V) to V1 (V) is detected, the charge control circuit 12 changes the setting of the switch 15 to the constant voltage source side, and changes the charging method to constant-voltage charging. If the charging current of a current voltage circuit falls down to A2 (A) or below while charging is being carried out with constant voltage, the charge control circuit 12 judges that charging has been completed and sets the switch 15 to off. If a notification of start of communication comes from a portable telephone circuit 11 while charging operation is underway, the charge control circuit 12 changes the setting of a switch 18 from the battery 3 side to the constant voltage source 14 side. <P>COPYRIGHT: (C)2004,JPO |
