> 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: Pieter Hoeben 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).
