Hi Ravinder! Really need more details to comment in detail. Consider the following, though:
1. Contact Discharge to the Horizontal Coupling Plane produces a large "bloom" of (mainly H-Field) radiation underneath the EUT. Could be on the order of 200 Volts/metre, depending on the spacing. Is the chassis open on the bottom? Can it be shielded? 2. Is the ASIC Integrated Circuit properly bypassed (very close) to its VDD pin(s)? 3. Are there any ribbon cables adjacent to the Horizontal Coupling Plane? Can they be re-routed? These are the first things I would check. Regards, Jim Ericson Acme Testing Company Acme, WA [email protected] > Hi ESD Gurus, > I am having problem with a controller card which is failing contact ESD > discharge at Negative 5 kV and below, but passes Positive contact discharge > unto 8 kV, and air discharge of either polarity up to 15 kV. The card is > mounted on an open metal chassis, and has DC input of 5V and 12V coming > from a power supply. The ground of the card is directly tied to the > chassis at several places. I am not discharging into the controller > chassis, but l place the unit on my ESD table and discharge into the > horizontal coupling plane, which results in the failure. > > Through my testing, I have isolated the problem to the main ASIC on the > card. An earlier version of the same card passes the test, whose ASIC is > built from the same CMOS process, but has a different processor core. It > is difficult to determine which part of the ASIC logic is latching up. I > have tried adding low value decoupling capacitors to power supply, but it > has no effect on the problem. > > Any suggestions on what I should I try next. > > Regards, Ravinder > Server PCB and Flex Development > Hitachi Global Storage Technologies This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
