Conformity Magazine - October 2007 - (Page 34)

modern high speed circuits. However, 2000V IEC stress is the minimum test level specified for system testing. Even with this minimum level of stress for IEC, the system level currents are several times larger than the HBM stress, although the HBM stress does continue for somewhat longer than the IEC stress. The peak CDM current comes closer to the peak current of the IEC stress and has similar rise time, but the duration of the IEC stress is almost 2 orders of magnitude longer. In some ways, the IEC system level stress looks similar to a combination of the fast rise time peak of CDM and the longer lasting current from HBM. As the stress levels for system level test are raised from the minimum level of 2000V to 8000V for IEC contact discharge, the higher level of stress for system level testing becomes even greater. Summary The current waveform stresses for some of the most common device and system level tests have been presented. It has been shown how system level testing, especially for IEC 61000-42, is much more severe than device level test, combining both the fast rise time and high peak current of a CDM event with the more long lasting currents of the HBM test. Knowledge of the waveform, no mater how complete, does not fully define the test. This is especially true for system level ESD testing. In order to upset or damage a system, the stress must reach a sensitive component. The stress must also be done in a way that approximates a real world event; otherwise, the test does not provide value. Robert Ashton is a senior protection and compliance specialist at ON Semiconductor, and can be reached at Robert.Ashton@onsemi.com. References 1. D. Pommerenke and M. Aidam, “To what Extent do Contact Mode and Indirect ESD Test Methods Reproduce Reality?” 1995 EOS/ESD Symposium, pp. 101-109. FAST Link www.conformity.com/1050 Figure 10: Comparison of ISO 61000-4-2 waveform with ISO 10605 waveforms with both 150pF and 330pF capacitances at 4000V Figure 12: Comparison of IEC, HBM and CDM waveforms Figure 11: Comparison of ISO 61000-4-2 waveform with ISO 10605 waveforms with both 150pF and 330pF capacitances at 8000V 34 Conformity oCtober 2007 Figure 13: Comparison of IEC, HBM and CDM at an expanded time scale http://www.conformity.com/1050

Table of Contents Feed for the Digital Edition of Conformity Magazine - October 2007

Contents Editor’s Note Commission Proposes Changes for 57-64 GHz Spectrum Rules FCC Continues Actions Against Jamming Device Distributors Radio Operator Fined for Failing to Make Equipment Available for Inspection Commission Fines Unsolicited Fax Advertisers Firm Offering Quality Standards Training Also Fined Breaking New Ground with Lithium-Battery Generic Requirements for Use in Telecommunications Facilities ESD Open Forum EMC UK 2007 Conference Set Staying Abreast of U.S. E-Waste Legislation EU Commission Establishes RFID Expert Group Update on China's CCC Compliance Program System Level ESD Testing: The Waveforms An Alternative Approach to Surge Suppression Testing Equipment Buyer's Guide EU Scientific Committee Releases Updated Data on EMF Risks Updated Standards List For The EU’s EMC Directive Updated Standards List For The EU’s Directives on Measuring Instruments Call for Presentations for 2008 International ESD Workshop Announced CPSC Actions In The News IEC Standards Update Product Reviews UL Standards Update New Products From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Upcoming Events Advertisers

Conformity Magazine - October 2007

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