| 摘要 |
PURPOSE:To obtain a temperature detecting circuit which can accurately detect the internal overheating state of a semiconductor element and, at the same time, can detect the fault of a temperature detecting section and output the abnormality. CONSTITUTION:A temperature detecting circuit detects the internal temperature of a semiconductor element by utilizing the negative temperature characteristic of a diode 11 and, when the temperature exceeds a certain value and the potential (V7) at a point 7 becomes higher than the potential (V9) at another point 9, the output voltage of an output terminal 13 is changed from an 'L' level to an 'H' level by turning on a transistor 10 and turning off another transistor 17 by using the differential output of a comparator composed of a first transistor 21 and second transistor 18. In case the potential V9 becomes abnormally high due to the opening state between both terminals of the diode 11 and exceeds a certain level V2 (the sum of the forward voltage VF (D19) of a diode 19 and the VBE (Tr20) of an output driving transistor 20), the transistor 20 wired-OR connected with the differential output transistor 10 is turned on and the output terminal 13 becomes an 'H' level. Therefore, the fault (open) of the temperature detecting circuit can be displayed. |
