2EL2, 2EL3, 2EL4
BIDIRECTIONAL THYRISTOR OVERVOLTAGE PROTECTORS
PRODUCT INFORMATION
1
AUGUST 1998Copyright © 1998, Power Innovations Limited, UK
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.
Manufactured by TI using silicon designed and manufactured by Power Innovations, Bedford, UK.
TELECOMMUNICATION SYSTEM PRIMARY PROTECTION
device symbol
T
R
SD4XAA
Terminals T and R correspond to the
alternative line designators of A and B
T(A)
R(B)
CELL PACKAGE
(SIDE VIEW)
MD4XANA
a71 Ion-Implanted Breakdown Region
Precise and Stable Voltage
Low Voltage Overshoot under Surge
a71 Rated for International Surge Wave Shapes
a71 Gas Discharge Tube (GDT) Replacement
DEVICE
V
(BR)
MINIMUM
V
V
(BO)
MINIMUM
V
V
(BO)
MAXIMUM
V
2EL2 ±245 ±265 ±400
2EL3 ±200 ±265
2EL4 ±215 ±265
DEVICE
ITU-T K28
(10/700)
GR-974-CORE
(10/1000)
I
TSP
A
I
TSP
A
2EL2 ±125 ±100
2EL3 ±125 ±100
2EL4 ±125 ±100
a71 Planar Passivated Junctions in a Protected Cell Construction
Low Off-State Current
Extended Service Life
a71 Soldered Copper Electrodes
High Current Capability
Cell Construction Short Circuits Under Excessive Current Conditions
description
These devices are primary protector components for semiconductor arrester assemblies intended to meet the
generic requirements of Bellcore GR-974-CORE (November 1994) or ITU-T Recommendation K28 (03/93).
To conform to the specified environmental requirements, the 2ELx must be installed in a housing which
maintains a stable microclimate during these tests (e.g. FIGURE I.1/K28).
The protector consists of a symmetrical voltage-triggered bidirectional thyristor. Overvoltages are initially
clipped by breakdown clamping until the voltage rises to the breakover level, which causes the device to
crowbar into a low-voltage on state. This low-voltage on state causes the current resulting from the
overvoltage to be safely diverted through the device. The high crowbar holding current prevents d.c. latchup
as the diverted current subsides. This 2ELx range consists of three voltage variants to meet various
maximum system voltage levels. They are guaranteed to voltage limit and withstand the listed international
lightning surges in both polarities.
These monolithic protection devices are constructed using two nickel plated copper electrodes soldered to
each side of the silicon chip. This packaging approach allows heat to be removed from both sides of the
silicon, resulting in the doubling of the devices thermal capacity, enabling a power line cross current capability
of 10 A rms for 1 second. One of the 2ELx’s copper electrodes is specially shaped to promote a progressive
shorting action (at 50/60 Hz currents greater than 60 A). The assembly must hold the 2ELx in compression,
so that the cell electrodes can be forced together during overstress testing. Under excessive power line cross
conditions the 2ELx will fail short circuit, providing maximum protection to the equipment.