DISCONNECTION DETECTING CIRCUIT

• Main Author: AOYANAGI KATSUHIKO
• Format: Patent
• Language: English
• Published: 02.05.1989
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PHYSICS; SIGNALLING; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION; TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILARSIGNALS

PURPOSE:To detect the disconnection of a transmission line and the disconnection of a power source line, etc., without fail by comparing the output level and the reference signal level of an absolute value circuit and equipping a device with a detecting circuit to detect the disconnection of the transmission line. CONSTITUTION:When the transmission line of a first signal A is disconnected and the level of the signal A does not become a high level, even the time t10 when the level is to become the high level comes, and remains in a low level, the output of a differential amplifier 1 becomes 0[V]. Therefore, the output of an absolute value circuit 2 also becomes 0[V], and this absolute value output signal (b) is sent to a comparator 10 of a detecting circuit 9 through a filter circuit 8. Since the absolute value output signal level becomes lower than the reference signal level in this comparator 10, a high level signal (c) is outputted from the comparator 10, and a high level signal X to indicate the occurrence of the disconnection is outputted from a D type flip-flop 12. Thus, the detection can be executed without fail even when both transmission lines are disconnected at the same time.