| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a charging circuit accurately detecting a fully charged state. Ž<P>SOLUTION: At the start of charging, a charging current control circuit 23 performs a constant current and constant voltage charging into a battery 40, with a switch 110 kept turned on. A CPU 31 decides whether a value of the charging current flowing into the battery 40 is lower than a switching threshold value (100 mA, for example), based on the voltage across a resistor 50 measured with a voltage detection circuit 22, and when the value of the charging current is decided lower than the switching threshold value, the CPU 31 turns off the switch 110 and controls a constant current control circuit 122 so as to perform constant current charging into the battery 40 with a comparatively small current (50 mA, for example). The CPU 31 decides whether the voltage of the battery 40 reaches the voltage (4.2 V, for example) indicating a full charged state on the basis of the voltage of the battery detected by a voltage detection circuit 121, and when it is decided that the full charged state of the battery 40 is achieved, the CPU 31 controls the constant current control circuit 122 to stop charging into the battery 40. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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