Non-isolated CAN bus overvoltage protection circuit

Abstract

The invention discloses a non-isolated CAN bus overvoltage protection circuit. The circuit comprises a CAN bus transceiver, a high and low position bus signal line connected to the CAN bus transceiver, a matching and filter circuit connected between the CAN bus transceiver and the high and low position bus signal line and an overvoltage protection circuit, wherein the matching and filter circuit is used for impedance matching among nodes and an electromagnetic interference of filtering common mode; and the overvoltage protection circuit is at least used for comparing a sampled bus common mode voltage and a reference voltage and cutting off or carrying out self recovery on bus signal transmission between the CAN bus transceiver and the high and low position bus signal line according to a comparison result. In the invention, a CAN bus electrical isolation (optoelectronic isolation or magnetic isolation) scheme does not need to be adopted, non-isolated overvoltage protection to the CAN bus transceiver and subsequent circuits is realized, cost of an isolation component is omitted and a CAN bus overvoltage protection scheme with low cost is realized; and simultaneously, an installation space required by the isolation component and the like are saved, and PCB and product layout difficulty is reduced, which is good for product size reduction.

Description

technical field [0001] The invention relates to a CAN bus overvoltage protection circuit, in particular to a non-isolated CAN bus overvoltage protection circuit. Background technique [0002] CAN is the abbreviation of Controller Area Network (hereinafter referred to as CAN), which is an ISO international standardized serial communication protocol. In the automobile industry, due to the requirements of safety, comfort, convenience, low pollution, and low cost, various electronic control systems have been developed. Since the data types used for communication between these systems and the requirements for reliability are not the same, there are many cases composed of multiple buses, and the number of wiring harnesses also increases accordingly. [0003] In order to meet the needs of "reducing the number of wiring harnesses" and "high-speed communication of large amounts of data through multiple LANs", the CAN communication protocol for automobiles was developed. Since then, ...

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Problems solved by technology

[0006] However, while electrical isolation improves the reliability of the CAN bus, it also brings a substantial increase in the cost of the communication circuit, whether it is traditional photoelectric isolation or more advanced magnetic isolation, so for some low-cost but high-reliability For high-performance applications, the isolation scheme is not suitable for

[0007] In addition, in order to meet the insulation requirements of the isolation voltage, a certain creepage distance and air gap need to be guaranteed in the PCB and product layout, which in turn means an increase in product volume

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