Triac technologies and immunity

AN3169

4/12

Doc ID 17194 Rev 1

1.2

Sensitivity and dV/dt immunity

This experimental comparison on immunity level has been performed on different devices

which target the same application. This application is the control of valves or pumps in white

goods. The load current is usually less than 1 A. Anyway, appliances designers use, to

control these loads, 1 A, 2 A and even 4 A Triacs. The use of a high current rating device is

usually motivated by desire for highly immune and robust systems.

To rationally compare the different devices, we have selected devices with the same voltage

minimum gate current that should be applied to turn on the device. The devices we have

The Triac sensitivity can not be reduced too much. An appliance designer has to work with

device will not be able to withstand excessive dV/dt rates across its power terminals (A1 and

A2 for Triacs, or OUT and COM for ACST). Triac manufacturers then give a dV/dt parameter

which is measured at the maximum junction temperature. Results of Table 1 are given for

dV/dt tests performed at a 125 °C junction temperature and a 400 V applied voltage. It

should be noted that some values are lower than values given in constructors datasheet for

the devices which are specified at 110 °C instead of 125 °C. This is a normal result as the

dV/dt immunity decreases with the temperature.

used during IEC 61000-4-4 tests, and for the different bias polarities.

The products tested are:

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the Z0409N: a top glass 4 A Triac

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the T410-800: a mesa glass 4 A Triac

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the ACST2: a planar 2 A Triac

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the COMP.1A: a planar 1 A Triac

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the COMP.2A: a planar 2 A Triac