7EL2
BIDIRECTIONAL THYRISTOR OVERVOLTAGE PROTECTORS
Copyright 漏 1999, Power Innovations Limited, UK
JANUARY 1999
TELECOMMUNICATION SYSTEM PRIMARY PROTECTION
q
Ion-Implanted Breakdown Region
Precise and Stable Voltage
Low Voltage Overshoot under Surge
V
(BR)
DEVICE MINIMUM
V
7EL2
鹵245
V
(BO)
MINIMUM
V
鹵265
V
(BO)
MAXIMUM
V
鹵400
CELL PACKAGE
(SIDE VIEW)
T(A)
R(B)
q
Rated for International Surge Wave Shapes
ITU-T K28
DEVICE
(10/700)
I
TSP
A
7EL2
鹵400
GR-974-CORE
(10/1000)
I
TSP
A
鹵300
MD4XACA
device symbol
T
q
q
Gas Discharge Tube (GDT) Replacement
SD4XAA
Planar Passivated Junctions in a Protected
Cell Construction
Low Off-State Current
Extended Service Life
R
Terminals T and R correspond to the
alternative line designators of A and B
q
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 7EL2 must be installed in a housing which
maintains a stable microclimate during these tests.
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. The 7EL2 is 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 7EL2鈥檚 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 7EL2 in compression,
so that the cell electrodes can be forced together during overstress testing. Under excessive power line cross
conditions the 7EL2 will fail short circuit, providing maximum protection to the equipment.
PRODUCT
INFORMATION
1
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.
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