To prevent a detection control circuit from being broken when excessive voltage is applied or input voltage in an inverse direction is applied to a rechargeable battery, and to attain size and weight reduction without requiring a high current capacity for a switching circuit.
The detection control circuit 15 includes a voltage detection circuit 11 for detecting charging voltage applied to the rechargeable battery; and a current detection circuit 12 for detecting charging current through the rechargeable battery. Charging control is performed by a transistor 3 on the basis of the detected output. The switching circuit 4 for protecting the detection control circuit 15 from the excessive input voltage or the input voltage in an inverse direction is provided in a ground line 26 of the detection control circuit 15. With this constitution, the charging current does not flow through the rechargeable battery, thus not needing high current capacity in the switching circuit. A circuit is also provided to eliminate a detection error due to internal resistance of the switching circuit 4.
COPYRIGHT: (C)2004,JPO
Kazuo Yamazaki
Tadahisa Yamamoto
ソニー・エリクソン・モバイルコミュニケーションズ株式会社
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