Design of silicon-based Transient Voltage Suppressor to meet IEC system-level ESD specification for RS485 transceiver

The Transient Voltage Suppressor (TVS) arrays are the best choice to protect RS485 interface transceiver. This paper proposes an On-Chip TVS (OCT) embedded in the half-duplex RS485 transceiver IC. It is composed of zener diodes and ordinary diodes and fabricated on 0.5μm CDMOS technology without extra process modification. RS485 transceiver with OCT has also been tested under the condition of IEC 61000-4-2 contact ±10kV stress and IEC 61000-4-4 Electrical Fast Transient (EFT) ±2KV stress. Results show no hard damage and latch-up issue. The RS485 transceiver chip occupies an area of 2.4×1.17mm².