From: Allan Herriman Newsgroups: comp.arch.fpga Subject: Lithium cell on Virtex2 Pro Date: Mon, 25 Aug 2003 22:53:41 +1000 Organization: Global Crossing Internet Lines: 12 Message-ID: <3f4a0737@dnews.tpgi.com.au> NNTP-Posting-Host: nnrp1.phx1.gblx.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: node21.cwnet.roc.gblx.net 1061816142 31360 64.214.31.40 (25 Aug 2003 12:55:42 GMT) X-Complaints-To: abuse@gblx.net NNTP-Posting-Date: Mon, 25 Aug 2003 12:55:42 +0000 (UTC) User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en X-Original-NNTP-Posting-Host: 203.219.10.94 X-Original-Trace: 25 Aug 2003 22:55:19 +1000, 203.219.10.94 Cache-Post-Path: nnrp1.phx1.gblx.net!203.12.160.33 X-Cache: nntpcache 2.4.0b5 (see http://www.nntpcache.org/) Path: chonsp.franklin.ch!pfaff2.ethz.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.mailgate.org!news-out1.nntp.be!propagator2-sterling!news-in-sterling.newsfeed.com!tdsnet-transit!newspeer.tds.net!nntp1.roc.gblx.net!nntp.gblx.net!nntp.gblx.net!news.globalcrossing.net!dnews.tpgi.com.au!tpg.com.au!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:32153 Hi, I notice that the maximum recommended Virtex2pro Vbatt is 2.63V. Lithium cells put out more than that. What are other designers doing about this? Is the solution as simple as a series Si diode on the Vbatt line? Thanks, Allan. ###### From: Austin Lesea Newsgroups: comp.arch.fpga Subject: Re: Lithium cell on Virtex2 Pro Date: Mon, 25 Aug 2003 07:41:00 -0700 Organization: Xilinx, Inc. Lines: 21 Message-ID: <3F4A1FFC.884CC8E1@xilinx.com> References: <3f4a0737@dnews.tpgi.com.au> NNTP-Posting-Host: 149.199.54.205 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.79 [en]C-CCK-MCD (Windows NT 5.0; U) X-Accept-Language: en Path: chonsp.franklin.ch!pfaff2.ethz.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.mailgate.org!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.media.kyoto-u.ac.jp!Spring.edu.tw!news.nctu.edu.tw!feeder.seed.net.tw!attdv1!ip.att.net!newsgate.xilinx.com!cliff.xsj.xilinx.com!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:32152 Allan, Yes, it is as simple as two series 1N914 or 1N4148 diodes (to make sure the voltage is dropped as the current is so low). Austin Allan Herriman wrote: > Hi, > > I notice that the maximum recommended Virtex2pro Vbatt is 2.63V. > Lithium cells put out more than that. > > What are other designers doing about this? > > Is the solution as simple as a series Si diode on the Vbatt line? > > Thanks, > Allan. ###### From: Allan Herriman Newsgroups: comp.arch.fpga Subject: Re: Lithium cell on Virtex2 Pro Date: Tue, 26 Aug 2003 10:26:42 +1000 Organization: Global Crossing Internet Lines: 28 Message-ID: <3f4aa99d@dnews.tpgi.com.au> References: <3f4a0737@dnews.tpgi.com.au> <3F4A1FFC.884CC8E1@xilinx.com> NNTP-Posting-Host: nnrp2.phx1.gblx.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: node21.cwnet.roc.gblx.net 1061857711 37680 64.214.31.41 (26 Aug 2003 00:28:32 GMT) X-Complaints-To: abuse@gblx.net NNTP-Posting-Date: Tue, 26 Aug 2003 00:28:31 +0000 (UTC) User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en In-Reply-To: <3F4A1FFC.884CC8E1@xilinx.com> X-Original-NNTP-Posting-Host: 203.219.10.94 X-Original-Trace: 26 Aug 2003 10:28:13 +1000, 203.219.10.94 Cache-Post-Path: nnrp2.phx1.gblx.net!203.12.160.33 X-Cache: nntpcache 2.4.0b5 (see http://www.nntpcache.org/) Path: chonsp.franklin.ch!pfaff2.ethz.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.mailgate.org!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.cwix.com!nntp1.roc.gblx.net!nntp.gblx.net!nntp.gblx.net!news.globalcrossing.net!dnews.tpgi.com.au!tpg.com.au!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:32207 Austin Lesea wrote: > Allan, > > Yes, it is as simple as two series 1N914 or 1N4148 diodes (to make sure > the voltage is dropped as the current is so low). > > Austin Thanks Austin. We'll try that. > Allan Herriman wrote: > > >>Hi, >> >>I notice that the maximum recommended Virtex2pro Vbatt is 2.63V. >>Lithium cells put out more than that. >> >>What are other designers doing about this? >> >>Is the solution as simple as a series Si diode on the Vbatt line? >> >>Thanks, >>Allan. > > ###### From: "kryten_droid" Newsgroups: comp.arch.fpga References: <3f4a0737@dnews.tpgi.com.au> Subject: Re: Lithium cell on Virtex2 Pro Lines: 23 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Message-ID: Date: Thu, 28 Aug 2003 11:27:36 +0100 NNTP-Posting-Host: 62.253.144.4 X-Complaints-To: abuse@ntlworld.com X-Trace: newsfep1-gui.server.ntli.net 1062066771 62.253.144.4 (Thu, 28 Aug 2003 11:32:51 BST) NNTP-Posting-Date: Thu, 28 Aug 2003 11:32:51 BST Organization: ntlworld News Service Path: chonsp.franklin.ch!pfaff2.ethz.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.imp.ch!news.imp.ch!newsfeed.stueberl.de!newspeer1-gui.server.ntli.net!ntli.net!newsfep1-gui.server.ntli.net.POSTED!53ab2750!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:32305 "Allan Herriman" wrote in message news:3f4a0737@dnews.tpgi.com.au... > I notice that the maximum recommended Virtex2pro Vbatt is 2.63V. > Lithium cells put out more than that. Many chips don't go to sleep mode until the VDD has dropped quite a bit. See: http://www.howell1964.freeserve.co.uk/MyHitachiPage.htm The 2V63 value might be the ideal value on their VDD/IDD graph, with most headroom for battery voltage droop, but lower voltages (e.g. 2V4) might work just as well. > Is the solution as simple as a series Si diode on the Vbatt line? Textbooks show zero current up to Vf but I suspect Vf drop depends on current, even before then. It should be a quick experiment to see what happens. ###### From: Allan Herriman Newsgroups: comp.arch.fpga Subject: Re: Lithium cell on Virtex2 Pro Date: Thu, 28 Aug 2003 22:41:57 +1000 Organization: Global Crossing Internet Lines: 44 Message-ID: <3f4df8f2$1@dnews.tpgi.com.au> References: <3f4a0737@dnews.tpgi.com.au> NNTP-Posting-Host: nnrp1.phx1.gblx.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: node21.cwnet.roc.gblx.net 1062074621 32654 64.214.31.40 (28 Aug 2003 12:43:41 GMT) X-Complaints-To: abuse@gblx.net NNTP-Posting-Date: Thu, 28 Aug 2003 12:43:41 +0000 (UTC) User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en In-Reply-To: X-Original-NNTP-Posting-Host: 203.219.10.94 X-Original-Trace: 28 Aug 2003 22:43:30 +1000, 203.219.10.94 Cache-Post-Path: nnrp1.phx1.gblx.net!203.12.160.33 X-Cache: nntpcache 2.4.0b5 (see http://www.nntpcache.org/) Path: chonsp.franklin.ch!pfaff2.ethz.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.mailgate.org!newsfeed.icl.net!newsfeed.fjserv.net!newshosting.com!news-xfer2.atl.newshosting.com!news-out.visi.com!petbe.visi.com!nntp1.roc.gblx.net!nntp.gblx.net!nntp.gblx.net!news.globalcrossing.net!dnews.tpgi.com.au!tpg.com.au!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:32285 kryten_droid wrote: > "Allan Herriman" wrote in > message news:3f4a0737@dnews.tpgi.com.au... > >>I notice that the maximum recommended Virtex2pro Vbatt is 2.63V. >>Lithium cells put out more than that. > > > Many chips don't go to sleep mode until the VDD has dropped quite a bit. > > See: http://www.howell1964.freeserve.co.uk/MyHitachiPage.htm Is this relevant to Virtex2pro? > The 2V63 value might be the ideal value on their VDD/IDD graph, with most > headroom for battery voltage droop, but lower voltages (e.g. 2V4) might work > just as well. The data sheet indicates voltages down to 1.0V are fine. >>Is the solution as simple as a series Si diode on the Vbatt line? > > > Textbooks show zero current up to Vf but I suspect Vf drop depends on > current, even before then. You might like to Google for the "diode equation". It will confirm your suspicion. BTW, you need better textbooks ;) Extrapolating a curve in the 1N914 datasheet gives about 120 - 130mV forward voltage at 100nA forward current. (This diode has an ideality factor of about 2.) The V2P data sheet indicates 100nA typical Ibatt over the recommended operating conditions. They don't specify a maximum current - I hope it's not 10uA or something. ;) Regards, Allan. ###### From: "kryten_droid" Newsgroups: comp.arch.fpga References: <3f4a0737@dnews.tpgi.com.au> <3f4df8f2$1@dnews.tpgi.com.au> Subject: Re: Lithium cell on Virtex2 Pro Lines: 25 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Message-ID: Date: Thu, 28 Aug 2003 15:14:13 +0100 NNTP-Posting-Host: 62.253.144.104 X-Complaints-To: abuse@ntlworld.com X-Trace: newsfep2-win.server.ntli.net 1062080096 62.253.144.104 (Thu, 28 Aug 2003 15:14:56 BST) NNTP-Posting-Date: Thu, 28 Aug 2003 15:14:56 BST Organization: ntlworld News Service Path: chonsp.franklin.ch!pfaff2.ethz.ch!pfaff.ethz.ch!news-zh.switch.ch!irazu.switch.ch!switch.ch!news-fra1.dfn.de!npeer.de.kpn-eurorings.net!newsfeed.freenet.de!194.168.4.91.MISMATCH!newspeer1-gui.server.ntli.net!ntli.net!newsfep2-win.server.ntli.net.POSTED!53ab2750!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:32271 "Allan Herriman" wrote in message news:3f4df8f2$1@dnews.tpgi.com.au... > > See: http://www.howell1964.freeserve.co.uk/MyHitachiPage.htm > Is this relevant to Virtex2pro? The bits about chips often having definite thresholds for low-power modes kicking in. > The data sheet indicates voltages down to 1.0V are fine. Great, a 2V4 batt should be fine then. > You might like to Google for the "diode equation". It will confirm your > suspicion. BTW, you need better textbooks ;) No insult to your intelligence intended. It's just that on most graphs of Vf/If, it does look flat below Vf threshold. > The V2P data sheet indicates 100nA typical Ibatt over the recommended > operating conditions. They don't specify a maximum current - I hope > it's not 10uA or something. ;) Even with 700 mV drop, a 2V4 batt should be fine. By the time it drops to 1V7, it is pretty much out of juice anyway.