2.3. Electrical Schematics.

Figure 2 : Electrical Schematics

The Transil may be unidirectional (Fig. 2 (A)) or

bidirectional (Fig. 2 (B)). In unidirectional form, it

operates as a clamping device in one sense and

like a rectifier in the other.

The Trisil may be designed to function with a

fixed breakover value (fig. 2 (c)) or a value which

can be programmed by the gate (fig.2(D)).

Figure 3 : Electrical behaviour in a Transil and a Trisil

For the same surge (A), figure 3 shows the

electrical behaviour of a Transil and a Trisil.

The parts (B) and (C) of figure 3 give the voltage

across the Transil and the current through it. It is

important to note that the current flows through

the protection device only during the clamping

phase. This

fact has to be taken into account

when the protector is chosen, because the

current duration is always shorter than that of

the overvoltage surge.

The parts (D) and (E) of figure 3 relate to the

Trisil behaviour. In this case the device fires

when

the

voltage

across

it

reaches

the

on-state until the current falls under the holding

during all of the on-state phase.

2.3. Electrical Behaviour.

(A)

(B)

TRANSIL

GATE

(C)

(D)

TRISIL

(A)

(B)

(C)

(D)

(E)

t

t

t

t

t

V

CL

V

BO

I

P1

I

P2

I

H

Surge

Voltage across the

TRANSIL

Current through the

TRANSIL

Voltage across the

TRISIL

Current through the

TRISIL

®

APPLICATION NOTE

2/4