RS485 communication is a commonly used communication method in the industry, widely applied with a simple circuit. Below is a circuit diagram of the 485 interface:
This image is one I found online; it is a commonly used circuit. Although many people use it this way and I haven’t heard of any issues, I believe there is a problem with this circuit, specifically with the three TVS diodes.
The TVS diodes in the diagram are rated at 6.8V, which I believe is inappropriate. In my circuit, I use 13V because, from the RS485 level conversion chip, I found:
The Differential Driver Output is a maximum of 5V under load conditions, but the Driver Output Voltage can reach a maximum of 12.5V. Therefore, when selecting TVS diodes, I always choose 13V.
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