Technical information

LCP1531

6/10

DocID13397 Rev 5

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 LCP1531 is equal to:

With:

The LCP1531 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. gives 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

LCP1531

100 nF

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

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

F=50Hz

t(s)

-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