>> 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: Uwe Zimmermann 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).
