Bourns® TBU® high-speed protectors (HSP), MOVs (metal oxide varistors), GDTs (gas discharge tubes), and TVSs (transient voltage suppressors) are introduced for RS-485 interface protection
This document explains how to protect RS‑485 communication lines from transient threats such as surge, ESD, and lightning. It introduces Bourns' TBU® high‑speed protectors, MOVs, GDTs, and TVS diodes, and shows how they can be combined into a three‑level protection architecture.
The note includes interface specifications, detailed protection schematics, transient surge test data, and two evaluation board designs. It also provides guidance on selecting primary and secondary protection devices and outlines the performance of the TBU protectors under various fault conditions. This manual is written in Chinese.
| Working voltage range | -7 V to +12 V |
|---|---|
| Maximum data rate | 32 Mbps |
| Maximum transmission distance | 1200 m |
| Response time of TBU protector | ≈1 µs |
| Surge current rating | >20 kA |
| Package size | 6.5 mm × 4 mm |
| Maximum voltage withstand | 265 V |
The protectors normally react within about 1 µs.
The interface is specified for a working voltage of –7 V to +12 V.