Datasheet

Technical information LCP1521S
6/10 DocID16804 Rev 3
The series resistors Rs1 and Rs2 designed in Figure 4 represent the fuse resistors or the
PTC which are mandatory to withstand the power contact or the power induction tests
imposed by the various country standards. Taking into account this fact the actual lightning
surge current flowing through the LCP is equal to:
I
surge
= V
surge
/ (R
g
+ R
s
)
With:
V
surge
= peak surge voltage imposed by the standard.
R
g
= series resistor of the surge generator
R
s
= series resistor of the line card (e.g. PTC)
e.g. For a line card with 30
Ω of series resistors which has to be qualified under
GR1089 core 1000V 10/1000 µs surge, the actual current through the LCP is equal to:
I
surge
= 1000 / (10 + 30) = 25 A
The LCP is particularly optimized for the new telecom applications such as the fiber in the
loop, the WLL, the remote central office. In this case, the operating voltages are smaller
than in the classical system. This makes the high voltage SLICs particularly suitable.
The schematics of Figure 6 give the most frequent topology used for these applications.
Figure 6. Protection of high voltage SLIC
Rs (*) = PTC or fuse resistor
Gn
GND
GND
TIP
RING
-Vbat
LCP1521S
220nF
SLIC
Rs (*)
Rs (*)
Line
Line card
TIP
RING
GND
Figure 7. Surge peak current versus overload
duration
Figure 8. Relative variation of holding current
versus junction temperature
I(A)
TSM
0
4
8
12
16
20
24
1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
t(s)
F=50Hz
T
j
initial=25°C
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
0.7
0.8
0.9
1
1.1
1.2
1.3
T (°C)
j
I [T ] / I [T =25°C]
Hj Hj