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 ;-)
Pieter Hoeben wrote: >>Hi, >>the board is 18 layer board. >>all the powering is done using the folowing scheme: >>1. all major power consumers have a sepparate "iland" under it (in one >>of the layers) connected to the main supply (ie 3.3 / 1.5V) with a >>Ferrite Bead, and a large capasitor (typicly 47uF tantalum) on both >>sides of te bead. in addition there are decoupling capacitors (0.1uf/ >>22pf) on each power terminal of the FPGA. >>All of the parts run from 120MHz clock distributed from CY2309. >>replacing the clock splitter with an industrial device, reduced the >>amounty of errors i get from the FPGAs. >>the power consuption is as folowing: showing the power line and >>consumption (where H stand for High and L for Low) >>/\ __/\ __ >> \/ \/ >>LHHHHHLHHHHH >> >>the rise of the graph is on LOW power consuption (i think it got some >>thing to do with the responce time of the Power Supply i.e.: it feels >>high current, but take time to stabilize the voltage level, so we see >>power drop. then the current fall and we see a power rise) >> >> > >To get an idea of the frequency, what is the risetime, up/down time >and falltime of this puls? > >Pieter > > > >> >> >>Pieter Hoeben wrote: >> >> >> >>>>here is a weered problem i stuck with developing a board of mine. >>>>it's a very heavy loaded board with many FPGA's on that "eat" a lot of >>>>power (100W) >>>>the problem is that those FPGA's do a heavy work once every 2msec wich >>>>creates power drop of about 0.2 volt. >>>>it results with the voltage looking like this: >>>>/\ ___/\ ___ >>>> \/ \/ >>>>where the mean voltage is 3.3V >>>> >>>> >>>> >>>Hi Michael, is the horizontal line the 3.3V? In that case >>>I do not only see a power drop, but also a power voltage rise? >>>That means that something may be reflecting, too much >>>inductance etc. Is it a multilayer with two power planes? >>> >>>You must use several capacitors, spread all over the board. >>>But do NOT place them neatly as you used to learn at school. >>>All those neat distances of th same length lead to a lot of >>>circuits with the same resonance frequency. If this is what >>>you have, user smaller and/or larger capaitors on several places. >>> >>>Regards, >>> >>>Pieter Hoeben >>> >>> >>> >>> >>>>anyone know how to deal with thease voltage dropout (thy cause >>>>malfunctioning of the curcit) >>>>Author: Michael Gefen >>>> INET: [EMAIL PROTECTED] >>>> >>>> >>>> >>>______________________________________________ >>> >>> Hoeben Electronics Phone: +31 6 51590081 >>> Ronkert 44 Fax: +31 13 5096025 >>> 5094 EW Lage Mierde Private: +31 13 5096200 >>> The Netherlands E-mail: [EMAIL PROTECTED] >>> http://www.hoeben.com >>>______________________________________________ >>> >>> >>> >>> >>> >>-- >>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). >> >> >> >> > > >______________________________________________ > > Hoeben Electronics Phone: +31 6 51590081 > Ronkert 44 Fax: +31 13 5096025 > 5094 EW Lage Mierde Private: +31 13 5096200 > The Netherlands E-mail: [EMAIL PROTECTED] > http://www.hoeben.com >______________________________________________ > > > > -- 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).
