| 摘要 |
PROBLEM TO BE SOLVED: To provide a detection switch which accommodates both NPN output transistor and PNP output transistor, and reliably detects an overcurrent. SOLUTION: A current direction switching circuit 38 comprising two current mirror circuits is provided between a transistor drive terminal 33 and an indication light drive terminal 34. The current direction between the terminals 33, 34 is changed by relating the operation of FETs 381D and 382D connected to construct current mirrors, and that of an FET 383 connected between the two terminals 33, 34 with the setting of a changeover switch 5. An overcurrent detection circuit 39 of which input is connected with the transistor drive terminal 33 judges that the excess current passes through an output transistor 41 in condition that an electric potential of the transistor drive terminal 33 is not less than a first threshold value and nor more than a second threshold value. COPYRIGHT: (C)2003,JPO
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