1/11
s
Dual bidirectional protection device.
s
High peak pulse current :
I
PP
= 40A (5/310
s SURGE)
I
PP
= 30A (10/1000
s SURGE)
s
Max. voltage at switching-on : 290V
s
Min. current at switching-off : 150mA
FEATURES
SO8
The
CLP30-200B1
is
designed
to
protect
telecommunication equipment. It provides both a
transient
overvoltage
protection
and
an
overcurrent protection.
The external components (balanced resistors, ring
relays contact, ...) needed by the CLP30-200B1
protection concept require very low power rating.
This results in a very cost effective protection
solution.
DESCRIPTION
OVERVOLTAGE & OVERCURRENT
PROTECTION FOR TELECOM LINE
July 1999 - Ed: 4
Any telecom equipment submitted to transient
overvoltages and lightning strikes such as :
s
Analog and ISDN line cards
s
PABX
MAIN APPLICATIONS
s
Voltage and current controlled suppression.
s
Surface Mounting with SO8 package.
s
Very low power rating of external components
on line card : balanced resistors, ring relay, low
voltage SLIC protection.
BENEFITS
1
TIPL
RINGL
TIPS
GND
GND
RINGS
GND
GND
SCHEMATIC DIAGRAM (Top view)
Application Specific Discretes
A.S.DTM
CLP30-200B1
CLP30-200B1
2/11
Overvoltage
reference
(> 200 V)
Overvoltage
detector
Overcurrent
detector
OR
Overvoltage
reference
(> 200 V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
RINGL
RINGS
GND
SW1
SW2
BLOCK DIAGRAM
Standard
Peak surge
voltage
(V)
Voltage
waveform
Required peak
current (A)
Current
waveform
Minimum
serial resistor to
meet
standard ( )
Bellcore TR-NWT-1089
First level
2500
1000
2/10s
10/100s
500
100
2/10 s
10/1000 s
20
25
Bellcore TR-NWT-1089
Second level
5000
2/10 s
500
2/10 s
40
ITU-T-K20 / K21
4000
1000
10/700 s
100
25
5/310 s
50
0
ITU-T-K20
(IEC61000-4-2)
6000
8000
1/60 ns
ESD contact discharge
ESD air discharge
0
0
VDE0433
4000
2000
10/700 s
100
50
5/310 s
50
5
VDE0878
4000
2000
1.2/50 s
100
50
1/20 s
22
0
IEC61000-4-5
4000
2000
4000
10/700 s
1.2/50 s
1.2/50 s
100
50
100
5/310 s
8/20 s
8/20 s
50
0
22
FCC Part 68, lightning
surge type A
1500
800
10/160 s
10/560 s
200
100
10/160 s
10/560 s
17.5
12
FCC Part 68, lightning
surge type B
1000
9/720 s
25
5/320 s
0
CLP30-200B1
3/11
telecommunication
"PRIMARY PROTECTION"
MDF
LINE CARD
EXCHANGE
line
SLIC
"SECONDARY PROTECTION"
CLP30-
200B1
VOLTAGE
REFERENCE
Fig.1 : Suscriber line protection topology
1.INTRODUCTION
The aim of this section is to show the behavior of
our new telecom line protection device.
Figure 1 is a simplified block diagram of a
subscriber line protection that is mainly used so
far.
This shows two different things :
s
A "primary protection" located on the Main Dis-
tribution Frame (MDF) eliminates coarsely the
high energy environmental disturbances (light-
ning transients and AC power mains distur-
bances) for which the ITU-T-K20 requires a 4kV
10/700
s test. This can be assumed either by
gas-tubes or silicon protection such as the
TLPxxM.
s
A "secondary protection" located on the line
card eliminates finely the remaining transients
that have not been totally suppressed by the
first stage. The ITU-T-K20 requires a 1 kV
10/700
s test. At this stage, the protection is
managed by the CLP30-200B1.
2. STMicroelectronics CLP30-200B1 CONCEPT
2.1 Evolution of the SLIC protection
Over the years, the performances of the SLICs
considerably increased and therefore the need of
the protection has also evolved.
The CLP30-200B1 is especially designed for the
protection of this new generation of SLIC. For this,
it is based on both overvoltage and overcurrent
protection modes.
The figure 2 summarises the performance of the
CLP30-200B1 which basically holds the SLIC
inside its correct voltage and current values.
- I
SWON
Programmable thanks to
an external resistor
Programmable thanks to
any external voltage reference
V
I
Line Card operating conditions
+ I
SWON
- V
SWON
+ V
SWON
Fig.2 : Line card protection
Pin
Symbol
Description
1
TIPL
TIP (Line side)
2 / 3 / 6 / 7
GND
Ground
4
RINGL
RING (Line side)
5
RINGS
RING (SLIC side)
8
TIPS
TIP (SLIC side)
APPLICATION NOTE
CLP30-200B1
4/11
Figure above shows the topology of a protected
analog subscriber line at the line card side.
s
A first stage based on CLP30-200B1 manages
the high power issued from the external surges.
When used in ringing mode, the CLP30-200B1
operates in voltage mode and provides a
symmetrical and bidirectional overvoltage
protection above 200 V on both TIP and RING
lines. When used in speech mode, the
CLP30-200B1 operates in current mode and
the activation current of the CLP30-200B1 is
adjusted by R
SENSE
.
s
A second stage which is the external voltage
reference device defines the firing threshold
voltage during the speech mode and also
assumes a residual power overvoltage
suppression. This stage can be either a fixed or
programmable device such as LCP1511D.
APPLICATION CIRCUIT : CLP30-200B1 in line card
RINGS
-Vbat
-Vbat
R sense
TIP
SLIC
Overvoltage
reference
(> 200 V)
Overvoltage
detector
Overcurrent
detector
OR
Overvoltage
reference
(> 200 V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
RINGL
GND
SW1
SW2
R sense
1
1
2
2
Ring
Generator
TIP
RING
External
voltage
reference
RING
I
Rp
Rp
R sense
R
R
PTC
PTC
Fig.3 : CLP30-200B1 in line card
CLP30-200B1
5/11
2.3 Ringing mode
In ringing mode (Ring relay in position 2), the only
protection device involved is the CLP30-200B1.
In normal conditions, the CLP30-200B1 operates
in region 1 of A1 curve, and is idle.
If an overvoltage occurring between TIP (or RING)
and
GND
reaches
the
internal
overvoltage
reference (+/- 200V), the CLP30-200B1 acts and
the line is short-circuited to GND. At this time the
operating point moves to region 2 for positive
surges (region 3 for negative surges). Once the
surge current disappears, the device returns to its
initial state (region 1).
For surges occurring between TIP and RING, the
CLP30-200B1 acts in the same way. This means
that
the
CLP30-200B1
ensures
a
tripolar
protection.
When used alone, the CLP30-200B1 acts at the
internal overvoltage reference level (+/- 200 V).
Furthermore, 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.5).
R sense
1
2
Overvoltage
reference
(>200V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
SW1
TIP
GND
I
LG
V
LG
1/2 CLP200M
I
LG
V
LG
1
2
3
-200
+200
A1
1
Fig.4 : Switching by voltage during ringing mode.
RINGS
R sense
1
2
Overvoltage
reference
(>200V)
Overvoltage
detector
Overcurrent
detector
OR
Overvoltage
reference
(>200V)
Overvoltage
detector
Overcurrent
detector
OR
TIPL
TIPS
RINGL
GND
SW1
SW2
R sense
1
2
TIP
RING
VZ1
VZ2
VZ3
VZ4
Fig.5 : Methode to adjust the reference voltage.
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