| 摘要 |
PURPOSE:To enable the objective circuit to detect temperatures with high accuracy without relaying on its manufacturing process by comparing a measured voltage with a reference voltage and, when the former exceeds the latter, outputting a prescribed detection voltage. CONSTITUTION:When a current flows to a transistor(Tr) Q8 through the resistor R4 of an actuation circuit 12, a voltage VBE is generated. The current flows to a Tr Q9 and the Q4 of a band-gap circuit 11 which are turned on by the voltage VBE and the voltage VBE is generated across the Tr Q4. The same current as the constant current I0 flowing through the Tr Q4 flows not only to Trs Q3, Q5, and Q6 which are turned on by the voltage BE, but also to Trs Q1 and Q2. The current I0 flowing through the Tr Q5 flows through a resistor R2 and the measurement voltage Va generated across both ends of the resistor R2 is inputted to the (+) terminal of the comparator 16 of a voltage comparator circuit 13. On the other hand, a reference voltage Vb is generated across the connecting point of the voltage dividing resistors R5 and R6 of the circuit 13 and inputted to the (-) terminal of the comparator 16. When the value of the voltage Vb is made equal to the voltage Va corresponding to a desirable detection temperature T, the output of the comparator becomes 'H' and it can be detected that a measured temperature exceeds the temperature T when the voltage Va becomes Va>Vb. |
