It has been a long time since I have done any work in this area but I still remember some generalities. The higher the power, generally the higher the emissions. See if there are low power options for your RAM and try them. Signal integrity and emissions are often linked. You may need to install damping resistors in you address/data lines. You may need to get an SI engineer to help particularly on your grounds on your 2 layer board.
Fred Townsend DC to Light [email protected] wrote: Hello everyone, I have a 2-layer PCB design, plastic enclosure, using 120 MHz SDRAM, two stuffing options: 2MB (16 Mb) in 50-pin tsop package or 8MB (64 Mb) in 52-pin tsop. It is slightly above class B radiated emission at the multiples of 120 MHz. I troubleshot it and I determined the SDRAM is the only source of the failing frequencies, everything else is quiet. I wonder if anyone has looked in how various manufacturers' memory chips perform emission-wise, particularly the type that I am using. I hope to find a manufacturer who makes "quieter" modules, so I do not need to change anything else on my board. If anyone has done such a comparison/investigation, I would appreciate if you would be willing to share, on-line or off-line, the results - which memory/manufacturer works best EMI-wise in such conditions. Regards, Neven - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc Text inserted by Platinum 2007: This message has NOT been classified as spam. If it is unsolicited mail (spam), click on the following link to reclassify it: It is spam! <http://127.0.0.1:6083/Panda?ID=pav_82075&SPAM=true> ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
