INTEGRATED SYMMETRICAL AND ASYMMETRICAL BIDIRECTIONAL OVERVOLTAGE
PROTECTORS FOR LUCENT TECHNOLOGIES L7581/2/3 LINE CARD ACCESS SWITCHES
Copyright © 1998, Power Innovations Limited, UK
JANUARY 1998 - REVISED OCTOBER 1998
OVERVOLTAGE PROTECTION FOR LUCENT TECHNOLOGIES LCAS
q Symmetrical and Asymmetrical
Characteristics for Optimum Protection of
Lucent L7581/2/3 LCAS
+105, -180 +130, -220
CUSTOMISED VERSIONS AVAILABLE
5 G MDXXAE
NC - No internal connection
q Rated for International Surge Wave Shapes
FCC Part 68
FCC Part 68
q Ion-Implanted Breakdown Region
Precise And Stable Voltage
Low Voltage Overshoot Under Surge
Terminals T, R and G correspond to the
alternative line designators of A, B and C
q Planar Passivated Junctions
Low Off-State Current < ±10 µA
q Small Outline Surface Mount Package
- Available Ordering Options
Taped and reeled
The TISPL758LF3 is an integrated combination
of a symmetrical bidirectional overvoltage
protector and an asymmetrical bidirectional
overvoltage protector. It is designed to limit the
peak voltages on the line terminals of the Lucent
Technologies L7581/2/3 LCAS (Line Card
Access Switches). An LCAS may also be
referred to as a Solid State Relay, SSR, i.e. a
replacement of the conventional electro-
The TISPL758LF3D voltages are chosen to give
adequate LCAS protection for all switch
conditions. The most potentially stressful
condition is low level power cross when the
LCAS switches are closed. Under this condition,
the TISPL758LF3D limits the voltage and
corresponding LCAS dissipation until the LCAS
thermal trip operates and opens the switches.
Under open-circuit ringing conditions, the line
ring (R) conductor will have high peak voltages.
For battery backed ringing, the ring conductor
will have a larger peak negative voltage than
positive i.e. the peak voltages are asymmetric.
An overvoltage protector with a similar voltage
asymmetry will give the most effective protection.
On a connected line, the tip (T) conductor will
have much smaller voltage levels than the open-
circuit ring conductor values. Here a symmetrical
voltage protector gives adequate protection.
Overvoltages are normally caused by a.c. power
system or lightning flash disturbances which are
induced or conducted on to the telephone line.
These overvoltages are initially clipped by
protector breakdown clamping until the voltage
rises to the breakover level, which causes the
Support from the Microelectronics Group of Lucent Technologies Inc. is gratefully acknowledged in the definition of
the TISPL758LF3D voltage levels and for performing TISPL758LF3D evaluations.
Information is current as of publication date. Products conform to specifications in accordance
with the terms of Power Innovations standard warranty. Production processing does not
necessarily include testing of all parameters.