IEC 61000-4-4 Tests

AN3169

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Doc ID 17194 Rev 1

Figure 7.

ACST2 turn on zoom (without input varistor)

2.3

Technology impact on immunity levels

Immunity test results according to P/N are given in Figure 8. This graphic gives the

maximum burst levels that the different devices were able to withstand before turn on. We

see that most of the devices present highly dispersed results. Even if these tests have been

Table 1), their immunity levels can vary with a 1 to almost 3 scale. The coupling mode and

burst polarity also have an impact on the immunity capability of a sample. This impact can

vary between 20 to 60%. Only the minimum value of the “maximum burst level” range, given

in Figure 8, should be taken into account. This minimum level corresponds to the worst-case

operation among all the different coupling cases covered by the IEC 61000-4-4 standard.

It should be also noted that the maximum capability of our burst generator is 4.5 kV. That

means that we didn't succeed in reaching the maximum immunity level of most ACST2

devices.

These results offer several interesting considerations.

●

The planar technology allows the highest level to be reached, but different companies

do not reach the same level.

●

ACST2 supports levels twice as high as its closest competitor (COMP.2A).

●

The 2 A device (COMP.2A) in planar technology is approximately as immune as the 4 A

Triac in mesa glass technology.

●

A device which presents a good dV/dt immunity (around 500 V/us for COMP.1A) can

only be as immune as a 4 A top device with a dV/dt capability close to 100 V/us.

Concerning the last point, it should be noted that the COMP.1A device presents a die area

which is approximately 20% lower than the Z0409. And generally speaking it can be said

that the bigger the die area is, the higher the immunity level is. Only the ACST2, which

presents the highest immunity level, presents also the highest “immunity-level-to-die-area”

ratio.

Indeed, its die area is almost half that of the T410-800 for twice the immunity.

Compared to COMP.2A, this “immunity-area” ratio is also 40% higher. To reach

approximately the same immunity level (2.4 KV in average, compare to 3 kV with ACST2), a

47 nF - 100 ohm snubber circuit has to be added across the COMP.2A device.

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