CLP200M_03 Datasheet, PDF (3/21 Pages) STMicroelectronics – OVERVOLTAGE AND OVERCURRENT PROTECTION FOR TELECOM LINE

CLP200M
APPLICATION NOTE
2. STMicroelectronics CLP200M CONCEPT
1. INTRODUCTION
The aim of this section is to show the behavior of
our new telecom line protection device. This de-
vice includes a primary protection level and is suit-
able for main distribution frames and line
cardsThis protection concept is explained and, in
addition, the CLP200M performances are ana-
lysed when facing different surges as described in
the CCITT recommendations.
Fig. 1 : Subscriber line protection topology
2.1 Evolution of the SLIC protection
Over the years, the silicon protection perfor-
mances have considerably changed.
The first generation of products like SMTHBTxx
and SMTHDTxx offered fixed overvoltage protec-
tion against surges on either TIP or RING line in
four packages.
The following generation like THBTxx and
THDTxx still offered fixed overvoltage protection
against surges on both TIP and RING lines in two
packages.
The next step was the introduction of the
"PRIMARY PROTECTION"
"SECONDARY PROTECTION"
LCP1511D which brought the advantage of full
telecommunication
CLP200M
SLIC
programmable voltage.
line
Today, the CLP200M combines the features of all
MDF
LINE CARD
EXCHANGE
uct(s) _{telecommunication}
Prod ^line
MDF
"SECONDARY PROTECTION"
CLP200M
THDTxx or
LPC1511D
or LB200B
SLIC
LINE CARD
EXCHANGE
olete _{Figure 1 is a simplified block diagram of a sub-}
s _{scriber line protection that is mainly used so far.}
b _{This shows two different things :}
- ^O s A “primary protection” located on the Main Distri-
) bution Frame (MDF) eliminates coarsely the
t(s ^{high energy environmental disturbances (light-}
ning transients and AC power mains
c _{disturbances)}
du ^{s A “secondary protection” located on the line card}
ro ^{includes a primary protection level (first stage) and}
a residual protection (second stage) which elimi-
P _{nates finely the remaining transients that have not}
te ^{been totally suppressed by the first stage.}
le ^{The CLP200M can be used both in MDFs and in}
line cards. In that case, any line card may be
so ^{swapped from one MDF to another one without re-}
bducing the efficiency of the whole system protec-
O^tion.
the previous generations. In addition to that, it of-
fers an overcurrent detection when operating in
speech mode and also a Failure Status output sig-
nal.
Fig. 2 : Line card protection
I
Programmable thanks to
any external voltage reference
+ I _SWON
Programmable thanks to
an external resistor
V
- I _SWON
Line card operating conditions
The figure 2 summarizes the performance of the
CLP200M which basically holds the SLIC inside its
correct voltage and current values.
The CCITT requirements are different for these
two protection locations (MDFs and line cards).
Concerning the “primary protection”, the CCITT re-
quires a 4kV, 10/700µs surge test whereas the
“secondary protection” has to withstand a 1kV,
10/700µs surge test.
The explanations which follow are basically
covering the line card application.
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