In a message dated 11/11/2003 5:48:57 PM Central Standard Time, drcuthb...@micron.com writes:
I do have a custom shielded test fixture that will allow the DIMM to be tested alone. Any desired READ or WRITE pattern can be used. The stimulus equipment resides in a shielded rack directly beneath the DIMM. The DIMM is mounted vertically and is free to radiate into the hemisphere above the rack. Now, what level do I test for? CISPR 22 ? I was told that a mother board can be CE Marked if it is <6dB over the limit. The theory being that the enclosure will (might?) provide >6dB of attenuation. If this is so then do I test the DIMM this way? The reason I asked about DIMMs is because after reading the appropriate documents I was convinced that it had to be tested and later changed my mind. Now I'm leaning towards testing being a requirement. Dave Cuthbert Micron Technology From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of POWELL, DOUG Sent: Tuesday, November 11, 2003 2:49 PM To: 'lfresea...@aol.com' Cc: emc-p...@majordomo.ieee.org Subject: RE: opinions, please Derek, Do you have a suggestion as to how the test should be performed? -doug Douglas E. Powell Corporate Compliance Dept. Advanced Energy Industries, Inc. Fort Collins, CO 80525 USA From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, November 11, 2003 8:56 AM To: john.radom...@modicon.com; mcinturff3...@msn.com Cc: emc-p...@majordomo.ieee.org Subject: Re: opinions, please In a message dated 11/11/2003 9:36:21 AM Central Standard Time, john.radom...@modicon.com writes: The EMC guidelines read: "... If the component is intended to be placed on the market as a single commercial unit for distribution and/or final use this function has to be available WITHOUT further adjustment or connections other than SIMPLE ones which can be performed by any person not fully aware of the EMC implications..." After seeing all the other list positings and thinking some more, I'm going to change my opinion on what this should be marked as. Originally, I said component. But... This is a module that when added to a PC brings new capibility. But, it also adds a path for noise to exit a system that the manufacturer may have tested ( if they even did ) differently. So I guess, I would say now that the module should be CE marked, and at a minimum, the contribution it makes to radiated emissions determined. I guess my second 2 cents worth.... Derek N. Walton Owner, L F Research EMI Design and Test Facility Poplar Grove, IL 61065 _______________________________________________________________ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. In Answer to Dave and Doug.. I did a whole bunch of plaing around measuring the SE of small shields and came to the conclusion that a fixture, radiating onto a small mode stirred chamber was the best way to get repeatable results. The bad side of this is that there is no "legal" limit to work with. I understand that there is an IC emissions test method in use in the automotive world, though I don't believe it has any standing in the EU. I guess my 8 cents now rests on testing the module in a PC chassis, with no enclosure "lid". And that leaves a bunch of questions.... The intent of the test would be to show thae the module does not radiate either noise made by itself, or, provide a path for noise from within the MB to escape. Sitting here, with a hot cup of Earl Gray tea.. I can't think why it would not be appropriate to apply the normal limits. With the advent of the plastic PC enclosures, you have to assume tha the case has 0 dB shielding.. I do like the idea of a fixture though, so that the module could be easily closed at different frequencies to see if there was a worst case. Back to my tea :-) Derek N. Walton Owner, L F Research EMI Design and Test Facility Poplar Grove, IL 61065
