APPLICATION NOTE

AN574/1197

TRANSIL

™/TRISIL™ COMPARISON

®

A. Bremond

1. INTRODUCTION

R

S

P

OVER-

-VOLTAGE

SOURCE

DEVICE

TO BE

PROTECTED

Figure1A : Classical schematic of parallel protection

To protect a sensitive device there are two

different approaches.

The first one is to use series protectors, the

second

one

parallel

suppressors.

The

technologies used in both cases are such

that the series devices are suitable for long

duration surges, while parallel protectors are

very efficient for the high current short

duration stresses which represent the great

majority of cases.

For the parallel protection solutions, two

philosophies can be used. The first one is

represented by a breakdown based device

and the second one by a breakover based

protector, respectively known as the Transil

and the Trisil.

Figure 1B : Electrical characteristics

2. TRANSIL / TRISIL COMPARISON

2.1. Electrical characteristics

I

V

-V

BR

V

BR

TRANSIL

I

V

-V

BO

V

BO

TRISIL

The

Transil

is

a

clamping

device

which

suppresses

all

overvoltages

above

the

The Trisil is a crowbar device which switches on

when overvoltages rise up to the breakover

voltage (

1/4