AN320

Trisil characteristics

Doc ID 5649 Rev 3

7/13

the power distribution network. This type of protection is required by certain standards used

in telecommunications.

Figure 9.

Long duration overload test

1.5

Response time

The response time of the component is the time it requires to limit the voltage. From this

point of view the Trisil has exactly the same behavior as a Transil. The time is that required

to switch from the standby operating point to the avalanche voltage. This is almost

instantaneous.

to the conducting characteristic. This time is longer but does not influence the limiting

capability of the device.

1.6

Operation within the avalanche area

This portion of the characteristic is identical to that of an avalanche diode. Thus within this

area, DC, AC or pulse-type operations are permitted. The currents are limited depending on

the possibilities of junction-ambient air heat dissipation. The maximum current is defined by

the following:

Equation 2:

The condition when the Trisil is not triggered is defined as follows:

Equation 3:

The main differences from Equation 1 are:

●

Maximum junction temperature which is now that given by the catalogue, i.e. 150 °C

●

Voltage which is that of the avalanche mechanism

●

Continuous thermal resistance replacing the transient thermal impedance

In AC operation, although Equation 2 still holds good, the voltage-current diagram as a

function of time shown in Figure 10 is clearer.

t(s)

I(A)

10

–10

F = 50 Hz

10 pair of pulses

1

12

1

12

180