| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching element protection circuit which can prevent deterioration in the characteristics or the breakdown of a switching element during high temperature operation, without increasing the size of the switching element. SOLUTION: The switching element protection circuit comprises a thermistor (11) for detecting the operating temperature of an MOS-FET (4), a comparison circuit (12) generating a maintenance signal, when the operating temperature detected by the temperature detection thermistor (11) exceeds a predetermined level, and a transistor (14) connected between two avalanche diodes (5, 6) for setting the detection voltage of an overvoltage protection circuit (10) and the control terminal (G) of the MOS-FET (4) and constituting a switching means (13) wherein the transistor (14) is turned on, when a maintenance signal is generated from the comparison circuit (12) and the detected voltage of the overvoltage protection circuit (10) is lowered. Since high-temperature operation of the MOS-FET (4) is switched to operation in the safe operating region of lowered detection voltage, deterioration in the characteristics or breakdown of the MOS-FET (4) can be prevented at high-temperature operation. COPYRIGHT: (C)2007,JPO&INPIT
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