| 摘要 |
PURPOSE:To combine overvoltage protection and voltage reduction protection to protect device internal circuits other than an abnormal position, by detecting rise or fall in the voltage inside circuits and by providing a protecting circuit which operates due to the difference between this voltage rise or fall and a comparison voltage. CONSTITUTION:The operation upper limit value of detecting voltage VD is determined by comparison between base voltage Vb1 of transistor Q1, which is given by the division ratio of resistances R3 and R4 and Zener voltage Vz for the overvoltage of detecting voltage VD and is given by the division ratio of resistances R1 and R2 for voltage reduction of detecting voltage VD, and base voltage Vb2 of transistor Q2 which is given by the division ratio of resistances R7 and R8 of comparison voltage VCC. The input to switching element Q3 is connected to the collector of transistor Q1 which is the output of the detecting circuit, thus controlling controlled device 9. |
