A Brief Introduction to EOS Testing International Standard IEC61000-4-5

In EMS (Electromagnetic Susceptibility) testing, crucial tolerance test items for external surge interference include Electrostatic Discharge (ESD) testing and Surge testing (EOS). ESD testing follows the IEC61000-4-2 standard, while EOS testing adheres to the IEC61000-4-5 standard.

IEC61000-4-5 defines standard EOS testing conditions, where the required open-circuit voltage and internal resistance can be set through a surge simulator. Common combined wave surge waveforms are categorized as follows:

1.????? The surge energy output by the simulator can measure a 1.2/50μs open-circuit voltage wave in open-circuit mode and an 8/20μs short-circuit current wave in short-circuit mode, as shown in Figure 1.

2.????? The surge energy output by the simulator can measure a 10/700μs open-circuit voltage wave in open-circuit mode and a 5/320μs short-circuit current wave in short-circuit mode, as shown in Figure 2.

EOS has consistently been one of the leading causes of failure in technological products. The material and time costs associated with resolving EOS issues are excessively high. Therefore, when EOS events occur, returned products or failed components from the production line are often provided to suppliers. Professional measurement and analysis, along with examination of the burnt area of components, are used to determine the magnitude of EOS energy, thereby providing effective EOS solutions.

Taking Amazing's AZC099-04S protection component as an example, as shown in Figures 3 and 4:

The IEC61000-4-5 standard defines surge testing requirements for power or signal lines in electronic products. Test specifications vary depending on the environment and signal characteristics, primarily simulating the impact on the system when EOS energy occurs. However, if the TVS protection component quickly activates when EOS energy enters the system, providing a low-impedance path to guide the EOS energy to ground through the TVS component, it will be the most effective way to protect electronic product systems. Therefore, when selecting a TVS protection component for EOS protection, it is essential to choose a TVS with IEC61000-4-5 EOS protection capabilities. The two main EOS protection parameters are as follows:

1.????? Ipp: The maximum surge current withstand capability of the TVS protection component (domestic and international TVS brand suppliers generally use the 8/20μs test waveform).

2.????? Surge clamping voltage: A smaller surge clamping voltage of the selected TVS protection component will provide better protection for the internal circuit.

Through the above explanation, it is hoped that readers can understand the key points of the IEC61000-4-5 standard. To pass this EOS test, the two most important EOS parameters of TVS components mentioned above can be used for material selection, which will enable the design of the most effective protection countermeasures.