Implementation and Practical Experience with an Automatic Secondary ESD Detection Algorithm

Secondary ESD from a non-grounded decorative metal structure on an electronic device often leads to very large discharge currents and a fast rise time of less than 400 picoseconds. Due to the proximity of this secondary ESD event to the electronics, it is likely to cause soft failures or latch-up. Secondary ESD can be detected in IEC 61000-4-2 setups by monitoring the currents, charge transfer, and sudden current increases due to the secondary ESD. An algorithm has been implemented in a test setup which automatically detects secondary ESD. However, due to pre-pulses, reignition of sparking within the relay, and other effects, the algorithm may lead to false positives and missed secondary ESD. This paper describes the implementation of the algorithm and presents the results of DUT testing.