A signal isolation barrier circuit

Abstract

The invention relates to a signal isolation grid circuit. An existing product only can realize an isolation effect or a surge protection effect. The signal isolation grid circuit comprises an automatic switching circuit, an interface circuit, an isolation power circuit, two surge protection circuits and two high-speed optocouplers; the automatic switching circuit comprises an AND gate chip, a NOT-AND gate chip, two RS-485 chips, four pull-up resistors, three pull-down resistors, matching resistors, a delay capacitor, a filter capacitor and a PNP-type triode; and the isolation power circuit comprises three isolation power sources, filter capacitors, matching resistors, a current limiting resistor, a delay capacitor, a TVS (transient voltage suppressor) diode, a PNP-type triode, a PMOS (P-channel metal oxide semiconductor) transistor, a light-emitting diode, a self-healing fuse and a gas discharge tube. The signal isolation grid circuit has the advantages that the three isolation power sources respectively supply power for a signal circuit at an intrinsic safety end, a signal circuit at a non-intrinsic safety end and a power circuit at the intrinsic safety end, complete isolation is implemented, and surge protection for the intrinsic safety end and short-circuit protection for power output ends are realized.

Description

technical field [0001] The invention belongs to the technical field of electricity and relates to a circuit, in particular to a signal isolation barrier circuit, which is applied to RS485 / RS422 signal protection in industrial control sites. Background technique [0002] With the parallel development of microprocessors and artificial intelligence technologies, the instrumentation industry is developing towards intelligence. Life is easier. With the development of science and technology, there are many types of instruments, which require a lot of manpower and material resources to copy the instrument data. Networking and remote transmission has become a new trend. [0003] Most industrial control meters use RS485 networking, which is convenient for networking and simple wiring. With the wiring, problems arise. The instrument is a precision device, and it is easy to introduce interference if the wiring is long, and the more serious one is lightning induction. When lightning...

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