there is some proccessing done by the FPGAs that involve large amount of IO changes (the I/O powered by the 3.3V). further information is posted in my previous mail (from about 30mins ago) Uwe Zimmermann wrote:
>>>The pulse happenes every 2ms >>>it's amplitude is about 300~400mV peak to peak. >>>so the risetime is about 0.4ms (from 3.3v to 3.5v) >>>yelding 0.8ms for the fall time (3.5v to 3.1v) >>>and then back to 3.3V >>>(well you get the idea ;-) >>> >>> > > > >>And what current runs? >> >> > > > >>Uwe is right about the ferrite beads. Make sure that you do >>not use the ones that act like coils, but that ones with a >>huge loss factor! Do use several elkos with low ESR, test >>with it to see if it makes a difference. See Uwe's email. >> >> > > > >>I do not think the beads are your problem here. A risetime >>of 0.4 ms means frequencys in the region of 2 kHz to 20 kHz. >>I expect ferrite bead problems in the MHz regions, not here. >> >> > >When I wrote my answer I was still unaware of the timing of the >pulses. > >If they really only appear every 2ms with rise and fall times in the >order of 1ms then the trace and ferrite bead inductance can be >neglected. There is no way these could be responsible for such huge >time constants. > >Are there any signals in the FPGAs which would explain sudden power >bursts with frequencies in the 1000Hz range? > > > Uwe. > > > > -- Author: Michael Gefen INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
