I'm using a VII Pro in a current project which requires the use of the RocketIO. This runs on 2.5V and I've selected a regulator, capacitors etc. in accordance with the RIO UG. Can I run other parts of the chip using the same regulator or should the RIO be considered special enough to warrant its own regulator and I need a 2nd 2.5V regulator for Vcco, Vccaux etc.? TIA, Rog.
Xilinx VIIPro power supplies
Started by ●April 13, 2005
Reply by ●April 13, 20052005-04-13
Reply by ●April 13, 20052005-04-13
Does it really? So I should have one 2.5V regulator for the RIO and another regulator for the 2.5V Vccaux etc.? I didn't realise. Thanks, Rog. <jason.stubbs@gmail.com> wrote in message news:1113416138.970557.20730@l41g2000cwc.googlegroups.com...> you must keep them seperate. The UG states this. >
Reply by ●April 13, 20052005-04-13
No. Are you gonna have a separate regulator for every single RIO you use? Of course you can use the same regulator, but you should consider isolating the noise from different (i.e. each RIO, Vccaux, Vcco) sections of your design. You might consider using a ferrite bead or two. www.murata.com Syms. "Roger" <enquiries@rwconcepts.co.uk> wrote in message news:fRe7e.21205$il.15556@newsfe5-win.ntli.net...> Does it really? So I should have one 2.5V regulator for the RIO andanother> regulator for the 2.5V Vccaux etc.? I didn't realise. > > Thanks, > > Rog. > > <jason.stubbs@gmail.com> wrote in message > news:1113416138.970557.20730@l41g2000cwc.googlegroups.com... > > you must keep them seperate. The UG states this. > > > >
Reply by ●April 13, 20052005-04-13
Extract from "The RocketIO=99 Transceiver User Guide UG024 (v2.5) December 9, 2004" "PCB Design Requirements (Page 109) To operate properly, the RocketIO transceiver requires a certain level of noise isolation from surrounding noise sources. For this reason, it is required that both dedicated voltage regulators and passive high-frequency filtering be used to power the RocketIO circuitry." If you dont use the RIO's you still have to supply power, but you can use the VCCAUX supply in this case. Hope this helps clarify the situation Jason
Reply by ●April 14, 20052005-04-14
Thanks for your replies. I was never considering 1 regulator per RIO but having never built anything that uses RIO before I'm keen to know what is considered best practice. I was just asking for opinions on the need (or otherwise) for a RIO regulator and a second "everything else on 2.5V" regulator. Looking at the recent replies, there seems to be some confusion. However as the UG seems to imply separate 2.5V regulators, maybe that's the way I should play it. Thanks, Roger "jason.stubbs" <jason.stubbs@gmail.com> wrote in message news:1113425021.561172.85090@z14g2000cwz.googlegroups.com... Extract from "The RocketIOT Transceiver User Guide UG024 (v2.5) December 9, 2004" "PCB Design Requirements (Page 109) To operate properly, the RocketIO transceiver requires a certain level of noise isolation from surrounding noise sources. For this reason, it is required that both dedicated voltage regulators and passive high-frequency filtering be used to power the RocketIO circuitry." If you dont use the RIO's you still have to supply power, but you can use the VCCAUX supply in this case. Hope this helps clarify the situation Jason
Reply by ●April 14, 20052005-04-14
Roger, The way I understood it, and therefore implemented it was to use a single linear regulator (LT1963) to power all of the RIO on the FPGA. If the LR is capable of supplying more than one FPGA's RIO circuitry, then that is acceptable. As long as all of the RIO supply pins are individually filtered with ferrite beads (and caps when they are not embedded), this should work. Under no circumstances should a switching regulator be used to power the RIO. Also, do not use the same LR that powers RIO to power the internal logic or IO of the FPGA. As you said in your earlier post, a linear reg for RIO, and a seperate reg for everything else. Regards Jason
Reply by ●April 14, 20052005-04-14
Jason, Thanks. That's very clear. Regards, Roger. "jason.stubbs" <jason.stubbs@gmail.com> wrote in message news:1113484269.095171.254220@l41g2000cwc.googlegroups.com...> Roger, > > The way I understood it, and therefore implemented it was to use a > single linear regulator (LT1963) to power all of the RIO on the FPGA. > If the LR is capable of supplying more than one FPGA's RIO circuitry, > then that is acceptable. As long as all of the RIO supply pins are > individually filtered with ferrite beads (and caps when they are not > embedded), this should work. Under no circumstances should a switching > regulator be used to power the RIO. Also, do not use the same LR that > powers RIO to power the internal logic or IO of the FPGA. > > As you said in your earlier post, a linear reg for RIO, and a seperate > reg for everything else. > > Regards > > Jason >
Reply by ●April 14, 20052005-04-14
Clear it may be, correct it's not. Switching regulators are just fine for RIO, as long as you provide for adequate filtering on the supplies. This may be easier than providing adequate heat sinking for linear regulators. As I said earlier. One big switching regulator for all your 2.5V, proper isolation and filtering to each RIO, Vccaux, each Vcco will work just fine. Sorry, I just get worked up when folks say 'under no circumstances'. It may well be that linear regulators are right for your design, but you should consider the options available to you. Cheers, Syms. "Roger" <enquiries@rwconcepts.co.uk> wrote in message news:R2v7e.781$v82.658@newsfe5-gui.ntli.net...> Jason, > > Thanks. That's very clear. > > Regards, > > Roger. > > "jason.stubbs" <jason.stubbs@gmail.com> wrote in message > news:1113484269.095171.254220@l41g2000cwc.googlegroups.com... > > Roger, > > > > The way I understood it, and therefore implemented it was to use a > > single linear regulator (LT1963) to power all of the RIO on the FPGA. > > If the LR is capable of supplying more than one FPGA's RIO circuitry, > > then that is acceptable. As long as all of the RIO supply pins are > > individually filtered with ferrite beads (and caps when they are not > > embedded), this should work. Under no circumstances should a switching > > regulator be used to power the RIO. Also, do not use the same LR that > > powers RIO to power the internal logic or IO of the FPGA. > > > > As you said in your earlier post, a linear reg for RIO, and a seperate > > reg for everything else. > > > > Regards > > > > Jason > > > >
Reply by ●April 14, 20052005-04-14
Syms, Thanks again for your input. I was actually intending to use linear LDO regulators in actual fact, as power and heat dissipation aren't an issue. However switching vs linear isn't really my query here. Basically, are you saying that I could supply my 4 RIOs, 4 x 3 Vcco pins and 4 Vccaux pins all from the same 2.5V LDO regulator (AVccaux RIO pins suitably filtered with Ferrite beads and capacitors of course)? Thanks, Roger. "Symon" <symon_brewer@hotmail.com> wrote in message news:425e91bf$1@x-privat.org...> Clear it may be, correct it's not. Switching regulators are just fine for > RIO, as long as you provide for adequate filtering on the supplies. This > may > be easier than providing adequate heat sinking for linear regulators. As I > said earlier. One big switching regulator for all your 2.5V, proper > isolation and filtering to each RIO, Vccaux, each Vcco will work just > fine. > Sorry, I just get worked up when folks say 'under no circumstances'. It > may > well be that linear regulators are right for your design, but you should > consider the options available to you. > Cheers, Syms. > > > "Roger" <enquiries@rwconcepts.co.uk> wrote in message > news:R2v7e.781$v82.658@newsfe5-gui.ntli.net... >> Jason, >> >> Thanks. That's very clear. >> >> Regards, >> >> Roger. >> >> "jason.stubbs" <jason.stubbs@gmail.com> wrote in message >> news:1113484269.095171.254220@l41g2000cwc.googlegroups.com... >> > Roger, >> > >> > The way I understood it, and therefore implemented it was to use a >> > single linear regulator (LT1963) to power all of the RIO on the FPGA. >> > If the LR is capable of supplying more than one FPGA's RIO circuitry, >> > then that is acceptable. As long as all of the RIO supply pins are >> > individually filtered with ferrite beads (and caps when they are not >> > embedded), this should work. Under no circumstances should a switching >> > regulator be used to power the RIO. Also, do not use the same LR that >> > powers RIO to power the internal logic or IO of the FPGA. >> > >> > As you said in your earlier post, a linear reg for RIO, and a seperate >> > reg for everything else. >> > >> > Regards >> > >> > Jason >> > >> >> > >
