一、Scheme protection circuit diagram

二、Application Environment

1. Indoor transmission line or transmission line from outdoor to indoor

2. Anti-static or anti-surge can be achieved by replacing the device

三、Explanation of the plan

RS232：

Anti-surge: RS232 is a common mode signal. If anti-surge is required, adding high-power TVS to the signal line can play a better anti-surge effect. The device is selected SMBJ15CA;

Anti-static: RS232 is a common mode signal. If anti-static is required, the device should be selected as an anti-static diode OVE2132P1, 12V/10pF/DFN1006 package, anti-static capability: air ±25KV; contact ±25KV,

RS485：

Anti-surge: R485 is a differential mode signal, which needs differential mode and common mode protection, TVS device selection SMBJ6.5CA;

Anti-static:

(1) TVS device selection anti-static diode OVE2632Q1, 7V/15pF/DFN1006 package;

(2) Select RS485 special protection device OVE6125QP1, protection voltage 7V/12V, SOT23 package