[SI-LIST] Re: 48V power distribution
- From: steve weir <weirsp@xxxxxxxxxx>
- To: Alexandre.Gourari@xxxxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Mon, 25 Oct 2004 12:04:49 -0700
Alexandre, within a converter design, that is correct. But on the board
that uses a converter as a component, the AC voltage is hidden.
Steve.
At 04:22 PM 10/25/2004 +0100, Gourari, Alexandre wrote:
>But I thought that Steve's original suggestion about safety on 48V was
>right. Given you are not going to use linear regulator to power logic from
>48VDC some sort of buck converter is necessary, so your voltage swing at the
>switcher will be >48VAC peak-to-peak (due to voltage drop on recirculating
>diodes) exceeding 42Vp-p safety threshold.
>
>Best regards,
>Alex Gourari
>
>-----Original Message-----
>From: steve weir [mailto:weirsp@xxxxxxxxxx]
>Sent: Friday, October 22, 2004 7:00 PM
>To: lorber@xxxxxx; tcuratolo@xxxxxxxx; si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: 48V power distribution
>
>
>Walter thanks. I went back and reviewed the standard. Stupid me, I have
>had 42.4VDC erroneously stuck in my head for a long time.
>
>As to Tom's question, I didn't see it before-
>
>Tom, an one issue that can come up is of battery return. One of the nice
>things about isolated power supplies at the card entry is that they
>facilitate a battery return isolated from the signal common. That frees
>one to tie the signal common to the package frame without a safety issue as
>the frame cannot become the battery return, and therefore doesn't carry
>risk of electrification. If you push the power converters inward, and you
>want to maintain this important safety characteristic, then you will still
>be stuck keeping the battery return DC isolated from the frame. It isn't
>the end of the world, but you will want to watch it. The other thing that
>I think you really want to look at is the physical size of the magnetics
>that will be needed, and I mentioned before.
>
>Regards,
>
>
>Steve
>At 04:34 PM 10/22/2004 -0500, Lorber, Walter wrote:
> >The SELV limit is 60VDC or 42.4VAC in IEC 60950
> >With best regards,
> >Walter
> >
> >
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> >On Behalf Of tompegbel
> >Sent: Friday, October 22, 2004 4:22 PM
> >To: si-list@xxxxxxxxxxxxx
> >Subject: [SI-LIST] Re: 48V power distribution
> >
> >
> >Thanks Steve, I appreciate your insight. I guess I really wanted to
> >focus on the issue of isolation versus non-isolation at the point of
> >entry for the PCB power distribution provided it is within SELV
> >limits. Provided components are available and cost of implemenation
> >is acceptably low, is there any major drawbacks with isolation at the
> >point of load versus isolation at the point of entry?
> >Regards,
> >--Tom
> >
> >--- In si-list@xxxxxxxxxxxxxxx, steve weir <weirsp@xxxx> wrote:
> > > Tom, the biggest issue is that 48V exceeds the 42V low-voltage
> >safety limit
> > > and so requires substantially greater clearances. A 24V system is
> >under
> > > that limit and does not face the same problem. 48V also changes
> >the
> > > dynamics of available semiconductors. 12V systems and to a certain
> >extent,
> > > 24V systems can leverage the super low on resistance and low
> >capacitance
> > > FETs and diodes. The last issue is one of magnetics and practical
> > > form-factors. Given you work for Vicor, you should be pretty
> >familiar with
> > > those and how taller primary to output ratios aggravate same.
> > >
> > > Regards,
> > >
> > >
> > > Steve
> > > At 02:04 PM 10/19/2004 +0000, tompegbel wrote:
> > >
> > > >Is there a good resource/document for addressing the concerns in
> > > >bussing 48V power in a multilayer board? The recently popular 12V
> >or
> > > >lower intermediate bus approach has limitations as voltages get
> >lower
> > > >and current gets higher. There appears to be new approaches of
> >using
> > > >a higher bus voltage (24V or 48V) for distribution since this was
> > > >explored in the 80's with the advent of distributed power and now
> > > >more recently with VoIP type designs. Any assistance appreciated
> > > >
> > > >
> > > >
> > > >------------------------------------------------------------------
> > > >To unsubscribe from si-list:
> > > >si-list-request@xxxx 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@xxxx 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
> > > >
> > >
> > >
> > > ------------------------------------------------------------------
> > > To unsubscribe from si-list:
> > > si-list-request@xxxx 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@xxxx 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
> >
> >
> >
> >------------------------------------------------------------------
> >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
> >
> >
> >
> >------------------------------------------------------------------
> >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
> >
>
>
>------------------------------------------------------------------
>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
>
>------------------------------------------------------------------
>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
>
------------------------------------------------------------------
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
Other related posts:
