short at 0.7 to 1 nanosecond (ns), with most of the energy dissipating within the first 30 ns, after which it rapidly
decays. Therefore, very fast- acting overvoltage protection is required for a timely response to ESD events.
Start with IEC standards To mitigate the risks of EFTs, the International Electrotechnical Commission (IEC) has defined three internationally recognized standards for overvoltage protection within IEC 61000-4 (“Electromagnetic compatibility (EMC): Testing and measurement techniques”): 1) IEC 61000-4-2 covers system- level ESD immunity, which applies to ESD caused by human contact (Figure 1). For this waveform, the rise time (tr) is
Figure 1: A typical ESD pulse waveform due to human contact, as characterized by IEC 61000-4-2, shows a very short rise time of less than a nanosecond, with most of the energy dissipating within the first 30 ns. (Image source: Eaton)
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