June 2014

DocID023640 Rev 2

1/14

AN4160

Application note

TVS devices for power line communication applications

Introduction

All communication applications are bound to comply with electro-magnetic compatibility

(EMC) standards, whose requirements depend on the application environment.

This Application Note aims at explaining how to use transient voltage suppressor (TVS)

devices to protect power line communication (PLC) circuits against electrical over-Stress

(EOS) and specifically against surge events as defined by IEC 61000-4-5 and EN50065-2-3

international standards.

Even though 4 kV test level is required as maximum withstand level by the aforementioned

application standards, for this Application Note a PLC circuit has been tested against 6 kV

surges; this higher level is often required by customers for higher confidence or specific

applications. Tests performed and results will be presented, focusing in the end on an

optimized PLC protection solution.

Application description

Power line communication can be used in various applications such as smart metering,

home automation, street lighting, solar inverters and so on.

In all cases, the PLC circuit will be coupled to a power line (AC or DC) with high probability

of high-energy transients, potentially causing EOS events that could damage the

application.

The application conditions described above create the need for specific protection devices

to be included in the power line coupling circuit.

Tests on adequate protection devices have been performed using the ST demonstration kit

EVALKITST7580-1. Built around the ST7580 power line networking system-on-chip, this

demonstration kit embeds all the functions required for a “turn-key” power line

communication network: the PLC node based on the ST7580, the AC power supply (based

on the ALTAIR4-900 chip) and the STM32 microcontroller, to either control the system as a

standalone application or to connect the EVALKITST7580-1 to an external host.

For all EVALKITST7580-1 documentation, including Application Note, schematics, and PCB

layout, please go to ST PLC products webpage or EVALKITST7580-1 webpage.

www.st.com