Today Xiaobian tage electronic technology to explore the problem we bring is "self recovery fuse protection application in RS-485 serial data interface".
We look down:
RS-232, RS-422 and RS-485 serial data interface standard, serial data interface in the application design, interface transmission lines are usually exposed to the outdoors, so it is very easy because of interference, voltage instability, load short-circuit, installation error, lightning and other reasons the over-voltage and damage of interface circuit. Once the overvoltage is introduced, it will breakdown. When there is a strong surge of energy, you can even see the transceiver burst, the line of the phenomenon of coke burning.
Therefore, it is necessary to consider the design of the interface of the serial interface of the current protection and the protection of lightning. As shown in the following reference diagram, the use of self recovery fuse and TVS tube as the over current protection and protection against lightning.
When an overcurrent or lightning event occurs, the overcurrent and overvoltage caused by A/B line, through the self recovery fuse and GDT as the primary common mode protection, usually GDT 10KA (8x20us) can withstand surge. After the residual pressure has been greatly reduced to below 1KV, then the TVS tube as the two level of protection of the cm / DM protection to the transceiver voltage clamped below 12V, at the same time, through the A/B line of the pull in voltage of the voltage can be kept in the A/B line is kept in high level, and realize the overcurrent and surge protection transceiver for.
Normally, for 4KV the following over voltage, you can save the primary protection - --GDT. TVS can achieve the requirements of surge protection. When the RS-485 bus is installed incorrectly or in connection with the power line (e.g. 220VAC). A/B online self recovery fuse can provide short circuit protection.
Small series of the story to this end, the future will continue to update the self recovery fuse over the flow of voltage and other technical combat experience sharing! Hope you pay attention to our official website http://www.sxyanhuqudpf.org.cn/enindex.htm electronic dance


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