| 摘要 |
PURPOSE:To protect the transmission circuit through the prevention of adverse effect on other circuits and components when logic elements cause latch-up, by providing an integrating circuit and a switching element at the output side of logic elements in multiplex transmission circuits. CONSTITUTION:The power supply from the transmission line is fed to a logic element 3 consisting of ICs via a rectifying circuit 1 and a smoothing circuit 2. At the output side of the logic element 3, the base of a transistor TR1 is connected via a resistor R3, the base of TR2 is connected to the emitter of TR1, the emitter and collector of TR2 are connected to the rectifying circuit 1 to form the protection circuit of multiplex transmission circuit. At the output side of the logic element 3 of this protection circuit, an integrating circuit 4 consisting of a resistor R1 and a capacitor C1, constant voltage element ZD and switching element are connected, and the element 5 is connected to the base of TR1. Further, the output of the integrating circuit 4 drives the element 5 to stop the transmission of current signal driving TR1, allowing to prevent the circuit from being damaged circuits and components due to latch-up logic element 3. |
