AN2266 Datasheet, PDF (1/16 Pages) STMicroelectronics – SLIC based system protection for European and Asian markets

AN2266
Application note
SLIC based system protection for European and Asian markets
Introduction
Even with the boom of the digital technologies and the wireless systems, telecom analog
lines remain the most used link to carry speech around the world. Following telecom
deregulation the market, traditionally managed by national telecom administrations, is now
open to new operators. This makes for an increase in new applications using this simple
and cost effective way to supply speech signals.
Figure 1. Classic analog telecom system Figure 2. New telecommunication system
topology
topology
Central office
Primary
protection
modules
SLICs
Line
Subscriber
terminal
Main distribution
frame
Subscriber
line cards
Subscriber Line
terminal
Subscriber ^Line
terminal
Subscriber Line
terminal
SLICs
Connection
Boxes
High speed
Digital link
Figure 1 shows the classic analog telecom system topology, where subscriber terminals are
linked to the central office (CO) by means of copper wires. Inside the CO, lines cross the
main distribution frame (MDF) and then are connected to subscriber line cards. In
subscriber line cards, lines are managed by subscriber line interface circuits (SLIC).
Figure 2 shows the new telecommunication system topology. In this case the long distance
carrying of signals is through modern digital lines like optical fiber, coax, WLL, and others,
while the local distribution is still using copper twisted pairs.
Despite the fact that in both cases the subscriber terminal is connected to the SLIC by
means of copper wires, the line length is quite different (a few hundred meters to a few
kilometers for the classic system and a few meters to a few tens of meters for the new
system topology). This difference in length of the subscriber terminal connection makes the
management of the signal amplitude and the SLIC different.
March 2014
DocID11830 Rev 2
1/16
www.st.com