I have only a basic understanding of EMC for avionics and I hope that another forum member can provide more information, but I am willing to contribute what I know.
First, I thought that RTCA/DO-160D superseded revision C about 10 years ago. Revision D updated the susceptibility testing, in particular the RF susceptibility test methods. Avionics tested to the older standard might not meet the new standard. Second, there have almost certainly been changes over the past 10 years that would significantly affect the EMC performance of any electronic device. One problem I have frequently encountered has been die shrinks >from the semiconductor manufacturers. As the semiconductor manufacturers move their highest performance parts to lines with smaller features, they are left with older fabrication lines with excess capacity. They often migrate all of their components to smaller feature sizes. It lets them get more dies out of a single wafer and increases profit. Often, everything is shrunk without changing the relative dimensions of the gates. This can affect susceptibility, and it can sharpen the edges increasing the broadband noise in emissions. The smaller gates and conductors can also be much more susceptible to EMC. In short, I would think it quite reasonable to requalify a design that is at least 10 years old. Ted Eckert American Power Conversion/MGE http://www.apc.com/ The items contained in this e-mail reflect the personal opinions of the writer and are only provided for the assistance of the reader. The writer is not speaking in an official capacity for APC-MGE or Schneider Electric. The speaker does not represent APC-MGE's or Schneider Electric's official position on any matter. Ken Javor <ken.javor@emccom pliance.com> To Sent by: <[email protected]> [email protected] cc Subject 12/13/2007 10:18 FAA TSO requirements PM Forum members, Lend me your ears. I am reviewing RTCA/DO-160C qualification data for some aircraft engine monitor gauges (rpm, temperature at various points). These devices date back ten years, plus they were qualified by similarity to an earlier design - how much earlier is not stated. My question is whether any forum members have a feel for how tight this TSO process really is. It is hard for me to imagine that every part in these gauges is built exactly like it was ten years ago, or more. I can see where the individual component part numbers would need to be the same, but is there any guarantee that the dc/dc converter manufacturer is building his product the same way, even if he uses the same part number? What about integrated circuits in general over such a span of years? Thanks in advance, Ken Javor Phone: (256) 650-5261 - 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 - 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
