Eddy - I agree it seems a little scary, but it just depends on what you're used to doing. I run ganged MegaLynx's (Tyco)rated at 30A each over 1 oz Cu planes, and still keep within the termal requirements using standard heat-sinking on the FPGAs. Fans are required. The board doesn't melt, and the noise isn't excessive if the board and PDS are designed correctly. I think you get more noise injection overdriving your inputs. But I do remember that when I first tried it....I had my fingers crossed. Ken -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Eddy Sent: Monday, June 18, 2007 9:37 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: HIGH DC Current on GND Plane "Saturation at DC is spelled meltdown" ROTFLMAO 60 Amps is an awful lot. That's like the current required to start a good size car! My first thought was "that has got be noisy as hell!". Theoretically the DC current should not cross-talk anything into your signal lines but I have a very hard time believing that 60 Amps of current can be quiet enough. However, I have seen Amps being confused with milli-Amps before.... 60 Amps is unrealistic to be flowing through a PCB. The copper would be curling off the FR4. There has to be a typo here somewhere.... Eddy --- "Townsend, Fred" <ftownsend@xxxxxxxxxxxx> wrote: > > I don't know the parties involved here but I think I > would start > analysis with psychoanalysis. It would take a lot of > convincing for me > to buy into this methodology. You don't say if the > 60 Amps is static but > if it changes there will certainly by cross talk! > Can you say ground > bounce? Normally one would want such current on the > outside of the board > where I would be looking for 4oz copper if your > vendor can supply it. > Saturation at DC is spelled meltdown. Have you done > temperature rise > analysis?=20 > > The only good news about this design I can see is > iron magnetically > saturates. Air and epoxy doesn't. > > Fred Townsend > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx > [mailto:si-list-bounce@xxxxxxxxxxxxx] > On Behalf Of Joe Paul M > Sent: Saturday, June 16, 2007 3:07 AM > To: si-list > Subject: [SI-LIST] HIGH DC Current on GND Plane > > > > I have a midplane carrying 60Amps of current and > Same GND plane is used=20 > as reference for multiple of 6.6 Ghz serdes lines , > PCI-e lines and GE > lines > Is there anything similar to 'saturation' in > Inductors applicable to GND > > plane? > ( Due to saturation of flux in the flux carrying > medium , beyond a=20 > certain amount of DC current inductors saturate and > wont act as=20 > inductors for any AC superimposed on the DC. ) > Will cross talk increase due to the absence of > mutual inductance between > > signals and gnd plane ? > Is there anything else that can go wrong due to this > DC , AC current=20 > mixing in planes ?? ____________________________________________________________________________ ________ Looking for earth-friendly autos? Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center. http://autos.yahoo.com/green_center/ ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu