2EL2, 2EL3, 2EL4

BIDIRECTIONAL THYRISTOR OVERVOLTAGE PROTECTORS

PR O D UC T

I N FO R M A T IO N

1

AUGUST 1998

Copyright © 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

q

Ion-Implanted Breakdown Region

Precise and Stable Voltage

Low Voltage Overshoot under Surge

q

Rated for International Surge Wave Shapes

q

Gas Discharge Tube (GDT) Replacement

DEVICE

MINIMUM

V

MINIMUM

V

MAXIMUM

V

2EL2

±245

±265

±400

2EL3

±200

±265

2EL4

±215

±265

DEVICE

ITU-T K28

(10/700)

GR-974-CORE

(10/1000)

A

A

2EL2

±125

±100

2EL3

±125

±100

2EL4

±125

±100

q

Planar Passivated Junctions in a Protected Cell Construction

Low Off-State Current

Extended Service Life

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 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.