Steve no its not company wide policy . its my opinion thats all.and it may differ from person to person also. the designer who decides finally which should get priority. and i decide like this. ok Thanks chand steve weir <weirsi@xxxxxxxxxx> wrote: Chand, is that a company wide policy? May I ask what company you work for? Steve At 10:52 PM 9/13/2006, chand basha wrote: charles, your are right both are equally importent. but we cant give equal priority to both and its not possible also. to ensure the smooth functioning of the board we put more priority to core. pcb engg cant do anything to affect the core power but he also cant assure the stability of the power ! ! ! now dont you feel core powe should be stable inorder to work the system properly ? Thanks chand "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx> wrote: I guess I'm confused. Aren't they ALL "important"? The core power and=20 the I/O power will have defined ripple specifications and so the PDS has to be designed to accommodate both. Best Regards Charles Grasso Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Pager/Short Message: 3032042974@xxxxxxxxx Email: charles.grasso@xxxxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [ mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Ken Cantrell Sent: Wednesday, September 13, 2006 8:22 AM To: Brad Crowell; Ken.Cantrell@xxxxxxxxxxxxxxxx; weirsi@xxxxxxxxxx; chand_374@xxxxxxxxx; zhuyongfa@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Cc: jinzhaoguo@xxxxxxxxxx; 'zhang kun@huawei' Subject: [SI-LIST] Re: which type of power(core logic power or I/O power) has a high priority Brad - The answer is the same on a single part basis. Ken Message----- From: Brad Crowell [ mailto:bcrowell@xxxxxxxxxxx] Sent: Wednesday, September 13, 2006 8:04 AM To: Ken.Cantrell@xxxxxxxxxxxxxxxx; weirsi@xxxxxxxxxx; chand_374@xxxxxxxxx; zhuyongfa@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Cc: jinzhaoguo@xxxxxxxxxx; 'zhang kun@huawei' Subject: RE: [SI-LIST] Re: which type of power(core logic power or I/O power) has a high priority Ken, But is that for IO or core power that is the most important? Which device is the biggest concern is a different question than which power rail to a given device is the biggest concern. Brad -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [ mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Ken Cantrell Sent: Wednesday, September 13, 2006 10:46 AM To: weirsi@xxxxxxxxxx; bcrowell@xxxxxxxxxxx; chand_374@xxxxxxxxx; zhuyongfa@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Cc: jinzhaoguo@xxxxxxxxxx; 'zhang kun@huawei' Subject: [SI-LIST] Re: which type of power(core logic power or I/O power) has a high priority Brad - Read the data sheet for the parts involved. See how much current and at what dI/dt each chip uses. The one(s) with the most/fastest current consumption are the ones that take priority. Ken -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [ mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of steve weir Sent: Wednesday, September 13, 2006 6:06 AM To: bcrowell@xxxxxxxxxxx; chand_374@xxxxxxxxx; zhuyongfa@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Cc: jinzhaoguo@xxxxxxxxxx; 'zhang kun@huawei' Subject: [SI-LIST] Re: which type of power(core logic power or I/O power) has a high priority Brad, I think you didn't see other responses because there is no correct rule of thumb answer. At the end of the day, one needs to analyze the requirements for all supplies. Often I/O needs priority. But, that is not something to depend on. Steve. At 04:47 AM 9/13/2006, Brad Crowell wrote: >I didn't see any other responses go by and was wondering if their were >any other opinions on this matter. From a PCB perspective, I would >suggest that the IO power would be more important. Not to suggest that >core power isn't also important, but there is less the PCB designer can >do to affect the quality of core power on an IC. To some degree, if the >chip designer hasn't taken care of the power supply design of the >IC/package, then the PCB cannot >fix it. Alternatively, the outputs are what induce currents on the PCB >and what the PCB designer should be more concerned with. I would be >interested in hearing other opinions. > >Thanks >Brad > >-----Original Message----- >From: si-list-bounce@xxxxxxxxxxxxx >[ mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of chand basha >Sent: Wednesday, September 06, 2006 6:45 AM >To: zhuyongfa@xxxxxxxxxx; si-list@xxxxxxxxxxxxx >Cc: jinzhaoguo@xxxxxxxxxx; zhang kun@huawei >Subject: [SI-LIST] Re: which type of power(core logic power or I/O >power) has a high priority > >zhuyongfa > its core logic power which will get the highest priority.(for >stabilised operation of the device) > > Thanks > chand > > >z46147 wrote: > Hi everyone, >In pcb design, there are several type of power(core logic power, I/O power). >In some designs we can not provide GND planes for each power type, when that >happens, which power type(core logic power, I/O power) we should give >priority to close with GND plane? As we all know, core logic power >always gives rise to EMI problem, and > >Thanks and regards! > >Zhuyongfa >Huawei Technologies Co., Ltd. >Bantian, Longgang District >Shenzhen 518129, P.R.China >Tel:+86-755-89650717 >mail:zhuyongfa@xxxxxxxxxx > > >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > >List technical documents are available at: > http://www.si-list.org > >List archives are viewable at: > //www.freelists.org/archives/si-list >or at our remote archives: > http://groups.yahoo.com/group/si-list/messages >Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > > > >--------------------------------- >Get your own web address for just $1.99/1st yr. 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