| 摘要 |
PROBLEM TO BE SOLVED: To provide a new and improved protecting circuit for an external battery pack, especially for the battery pack for a cellular phone. SOLUTION: The protecting circuit is equipped with: an assembly of switches which controls the connection of the output of a battery pack with a load; a detector which detects a resistance at the terminal of the load; a first comparator which generates a first output signal when it compares a resistance having a predetermined maximum value with the detected resistance, and the latter is larger than the former, and generates a second output signal when the latter is smaller than the former, a second comparator which generates a third output signal when it compares a resistance having a predetermined minimum value with the detected resistance, and the latter is smaller than the former, and generates a fourth output signal when the latter is larger than the former; and a second detector which is connected with the respective comparators and generates a controlling signal for closing the assembly of switches when the value of the detected resistor exists inside a scope between the maximum value and the minimum value, and generates a controlling signal for opening the assembly of switches when the value of the detected resistance exists outside the scope. COPYRIGHT: (C)2010,JPO&INPIT
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