AN578 Datasheet, PDF (1/5 Pages) STMicroelectronics – POWER CROSSING BEHAVIOUR OF LINE CARD PROTECTION

AN578
APPLICATION NOTE
POWER CROSSING
BEHAVIOUR OF LINE CARD PROTECTION
INTRODUCTION
The purpose of this document is to explain the behaviour of LCP 150S/1511/1512 devices during the cou-
pling between a telecommunication line and a mains line.
TEST DIAGRAM
Figure 1 shows the test diagram. The mains 220 V 50 Hz is applied to the test assembly through an iso-
lation transformer. A relay driven by a mono-pulse generator allows the conducting time to be adjusted.
The current through the device is adjusted by a series resistor.
Figure 1. Test Diagram
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220V
50Hz
ISOLATION
TRANSFORMER
RELAY
0 to 4K
Line A
LCPxxx
GND
+
-
POWER SUPPLY
48V
G AT E
MEASUREMENTS
During the tests three kinds of behaviour occur:
a) As shown in Figure 2 the device acts as a clamping device (non-firing) due to the small value of the
current which never exceeds the latching current of the structure.
May 2004
REV. 2A - 3601
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