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CLP200M
OVERVOLTAGE AND OVERCURRENT
PROTECTION FOR TELECOM LINE
Application Specific Discretes
A.S.D.
PowerSO-10
TM
NC
FS
TIP
S
RING
S
TIP
L
TIP
L
TIP
L
RING
L
RING
L
RING
L
TAB is connected to GND
1
SCHEMATIC DIAGRAM
July 2003- Ed : 4B
Any telecom equipment submitted to transient
overvoltages and lightning strikes such as :
s
Analog and ISDN line cards
s
PABX
s
Main Distribution Frames
s
Primary protection modules
MAIN APPLICATIONS
The CLP200M is designed to protect telecommu-
nication equipment. It provides both a transient
overvoltage protection and an overcurrent protec-
tion.
It is housed in a PowerSO-10
TM
package.
DESCRIPTION
s
Dual bidirectional protection device.
s
High peak pulse current :
ipp = 100a (10/1000
s surge)
s
Max. voltage at switching-on : 290v
s
Min. current at switching-off : 150ma
s
Failure status output pin
FEATURES
s
Both primary and secondary protection levels in
one device.
s
Voltage and current controlled suppression.
s
Surface
Mounting
with
PowerSO-10
TM
p a c k a g e .
s
Line card cost reduction thanks to the very low
power rating of external components required :
balanced resistors, ring relay, low voltage SLIC
protection
BENEFITS
CLP200M
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BLOCK DIAGRAM
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
RINGL
RINGS
FS
GND
SW3
SW1
SW4
SW2
Pin
Symbol
Description
1
FS
Failure Status
2
TIPS
TIP (SLIC side)
3 / 4 / 5
TIPL
TIP (Line side)
6 / 7 / 8
RINGL
RING (Line side)
9
RINGS
RING (SLIC side)
10
NC
Not connected
TAB
GND
Ground
COMPLIES WITH THE
FOLLOWING STANDARDS:
Peak Surge
Voltage
(V)
Voltage
Waveform
(
s)
Current
Waveform
(
s)
Admissible
Ipp
(A)
Necessary
Resistor
(
)
CCITT K20
6000
10/700
5/310
150
-
VDE0433
6000
10/700
5/310
150
-
VDE0878
4000
1.2/50
1/20
100
-
IEC61000-4-5
6000
4000
10/700
1.2/50
5/310
8/20
150
100
-
-
FCC Part 68
1500
800
10/160
10/560
10/160
10/560
200
100
-
-
BELLCORE TR-NWT-001089
2500
1000
2/10
10/1000
2/10
10/1000
500
100
-
-
CLP200M
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"PRIMARY PROTECTION"
"SECONDARY PROTECTION"
MDF
LINE CARD
telecommunication
EXCHANGE
line
"SECONDARY PROTECTION"
MDF
LINE CARD
telecommunication
EXCHANGE
line
CLP200M
SLIC
THDTxx or
LPC1511D
or LB200B
SLIC
CLP200M
Fig. 1 : Subscriber line protection topology
- I
SWON
Programmable thanks to
an external resistor
Programmable thanks to
any external voltage reference
V
I
Line card operating conditions
+ I
SWON
Fig. 2 : Line card protection
APPLICATION NOTE
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.
Figure 1 is a simplified block diagram of a sub-
scriber line protection that is mainly used so far.
This shows two different things :
s
A "primary protection" located on the Main Distri-
bution Frame (MDF) eliminates coarsely the
high energy environmental disturbances (light-
ning
transients
and
AC
power
mains
disturbances)
s
A "secondary protection" located on the line card
includes a primary protection level (first stage) and
a residual protection (second stage) which elimi-
nates finely the remaining transients that have not
been totally suppressed by the first stage.
The CLP200M can be used both in MDFs and in
line cards. In that case, any line card may be
swapped from one MDF to another one without re-
ducing the efficiency of the whole system protec-
tion.
The CCITT requirements are different for these
two protection locations (MDFs and line cards).
Concerning the "primary protection", the CCITT re-
quires a 4kV, 10/700
s surge test whereas the
"secondary protection" has to withstand a 1kV,
10/700
s surge test.
The explanations which follow are basically
covering the line card application.
2. STMicroelectronics CLP200M CONCEPT
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
LCP1511D which brought the advantage of full
programmable voltage.
Today, the CLP200M combines the features of all
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.
The figure 2 summarizes the performance of the
CLP200M which basically holds the SLIC inside its
correct voltage and current values.
CLP200M
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RINGS
-Vbat
-Vbat
Rp
R sense
TIP
1
1
2
2
SLIC
(*)
(*) LCP1511D or THDT series
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
RINGL
FS
GND
SW3 SW1
SW4 SW2
R sense
Rp
Ring
Generator
Fuse
Fuse
TIP
RING
External
voltage
reference
RING
I
APPLICATION CIRCUIT : CLP200M in line card
Fig. 3 : CLP200M in line card
Figure 3 above shows the topology of a protected
analog subscriber line at the exchange side. The
CLP200M is connected to the ring relay via two
balanced Rp resistors, and to the Subscriber Line
Interface Circuit. A second device is located near
the SLIC : it can be either a LCP1511D or a THDT
series.
These two devices are complementary and their
functions are explained below :
s
The first stage based on CLP200M manages
the high power issued from the external
surges. When used in ringing mode, the
CLP200M operates in voltage mode and pro-
vides
a
symmetrical
and
bidirectional
overvoltage protection at +/-215 V on both TIP
and RING lines. When used in speech mode,
the CLP200M operates in current mode and
the activation current of the CLP200M is ad-
justed by R
SENSE
.
s
The second stage is the external voltage refer-
ence device which defines the firing threshold
voltage during the speech mode and also as-
sumes
a
residual
power
overvoltage
suppression. This protection stage can be either
a fixed or programmable breakover device. The
THDTxx family acts as a fixed breakover device
while the LCP1511D operates as a programma-
ble protection.
Thanks to this topology, the surge current in the
line is reduced after the CLP200M. Because the
remaining surge energy is low, the power ratings of
Rp, the ring relay contacts and the external voltage
reference circuit may be downsized. This results in
a significant cost reduction.
CLP200M
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R sense
Rp
1
2
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
FS
SW3 SW1
Fuse
TIP
GND
I
LG
V
LG
1/2 CLP200M
I
LG
V
LG
1
2
3
-215
+215
A1
2.3 Ringing mode
Fig. 4 : Switching by voltage during ringing mode.
RINGS
R sense
Rp
1
2
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
Overvoltage
reference
(+/- 215 V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
RINGL
FS
GND
SW3 SW1
SW4 SW2
R sense
1
2
Rp
Fuse
Fuse
TIP
RING
VZ1
VZ2
VZ3
VZ4
Fig. 5a : Method to adjust the reference voltage.
In ringing mode (Ring relay in position 2), the only
protection device involved is the CLP200M.
In normal conditions, the CLP200M operates in re-
gion 1 of A1 curve, and is idle.
If an overvoltage occuring between TIP (or RING)
and
GND
reaches
the
internal
overvoltage
refe-rence (+/- 215V), the CLP200M acts and the
line is short-circuited to GND. At this time the oper-
ating point moves to region 2 for positive surges
(region 3 for negative surges). Once the surge cur-
rent disappears, the device returns to its initial
state (region 1).
For surges occuring between TIP and RING, the
CLP200M acts in the same way. This means that
the CLP200M ensures a tripolar protection.
When used alone, the CLP200M acts at the inter-
nal overvoltage reference level (+/- 215V). Fur-
thermore, it is possible to adjust this threshold level
to a lower voltage by using :
.
up to 4 fixed external voltage reference (V
Z1
to
V
Z4
) (see fig.5a).
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