2.4. Power dissipation

The dissipated power in both the Transil and the

Trisil is due to the presence of voltage across

and current through the protection device.

Note

that

for

the

same

package,

the

current-handling capability of a Transil depends

on the breakdown voltage, whereas this is not

the case for a Trisil.

For example, with the CB429 package we have

the Transil series 1.5 KE and the Trisil family

TPB which have different behaviour in terms of

current suppression.

As shown in table 1 the current rating of TPB

Current capability for 1ms wave

10V

62V

150V

220V

Transil

1.5KE

103A

17.7A

7.2A

4.6A

Trisil

TPB

100A

100A

100A

Table 1 : Current capabilities of Transil 1.5KE

and Trisil TPB

Tables 2 and 3 summarize the different

behaviour and advantages of both Transil

and Trisil devices. It is not possible to say

"Transils are better than Trisils" or the

opposite, only that their application areas

are different. SGS-THOMSON produces

both types of devices meeting the widest

protection requirements range.

3. SUMMARY

TRANSIL

TRISIL

TYPE OF ACTION

CLAMPING

CROWBAR

ELECTRICAL

CHARACTERISTICS

SCHEMATICS

ELECTRICAL

BEHAVIOUR

ACTION START

ACTION STOP

I < Holding Current

Table 2 : Transil/Trisil Summary

I

V

-V

BR

V

BR

OR

V

CL

I

V

-V

BO

V

BO

GATE

OR

V

BO

TRANSIL

TRISIL

No short - circuit

across low - impedance

lines , eg - power - supply.

Greater power handling

due to lower voltage

across terminals.

No need to ensure

device switch - off after

transient subsides.

Available

with

program-

mable breakover voltage.

Table 3 : Transil/Trisil distinctive advantages

®

APPLICATION NOTE

3/4