Wale, There aren't any hard document requirements that I know of but practically this is a bad idea.
Putting components (esp EMI filters) on the backplane is generally a bad idea for a few reasons: The first is (as pointed out by Jeff Collins) reliability and availability. You don't want to bring a unit out of service to change the backplane. Kind of creates availability issues. Other issues could easily arise such as - maybe your EMI filter doesn't work and you need to redesign it. You just rev'ed your backplane. Woo-hoo. T&V gets a major setback...it's just an ugly situation. Here's an approach I used at my last job where I was the guy for compliance and reliability/availability (don't worry, company & product are gone so I'm not revealing any secrets here). We designed the backplane from the get-go to accept rear daughtercards for EMI filters, I/O cables/filters, and the like. This allowed for easy replacement, re-work, and redesign of filters and active circuits when needed but still kept the circuits in the 'out of the way' locations on the back side of the backplane. The other benefits of daughter card was the ability to manipulate ground planes and filtering as desired without impacting impedances or routing on the backplane. Also, the real estate needed for a connector is much less than the real estate needed for actual circuitry so the layout guys stay happy(er) too. Just make sure that whatever you do, you do in a redundant fashion so you don't bring the system down when you have to change a part. Best Regards, -Dave Heald >>> wale aderemi <walest...@yahoo.com> 02/03/04 01:06PM >>> Please I need a document or requirement form either US(NEBS, etc) or International(ETSI, etc) that specifically states that a backplane must be passive or free of components. My employer started by putting an eprom on the backplane, and now due to EMI issues (and space consrains) wants to put an EMI power line filter consisting of capacitors, Inductors and Resistors on the backplane. I am resisting, and I have been challenged to show any document that says this is unacceptable. Thanks, Wale Aderemi Do you Yahoo!? Yahoo! SiteBuilder - Free web site building tool. Try it! ________________________________________________________________________ This email has been scanned for computer viruses. ________________________________________________________________________ This email has been scanned for computer viruses. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
