| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost by canceling an input DC offset voltage of an amplifier for detecting a charging current with no temperature fluctuation, eliminating the need for adjusting at shipping, and omitting a large scale circuit such as an A/D converter and a CPU. SOLUTION: A resistor 5 is connected in series to a battery 4. A zero voltage is inputted between both input terminals of an amplifier 6 in a first phase, while the charging current detection voltage that appears at the resistor 5 is inputted between both input terminals of the amplifier 6 in a second phase using a switch 9. A second switch 10 is closed in the first phase to write an output voltage of the amplifier 6 into a voltage storage element 8. A third switch 11 whose one end is connected to the output terminal of the amplifier 6 is closed in the second phase. A voltage at the other end of the third switch 11 added with a reference voltage 14 which regulates a stop point for charging operation is compared to the storage voltage of the voltage storage element 8 using a comparator 7, and the output of the comparator 7 is held by a latch circuit 12. COPYRIGHT: (C)2003,JPO
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