[SI-LIST] Re: Current sense resistors and power integrity

Dave-

Where are you getting your 3mOhm 1206 resistors ?? :)

If he is measuring current, he'd probably want pretty tight R tolerance
(say < 2%). Perhaps a carefully design trace section whose R is
nominally 3 mOhms would be the way to go.....

-Ray
Xilinx Inc.


> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of DAVID CUTHBERT
> Sent: Friday, August 22, 2008 12:11 PM
> To: Mikhail Matusov
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Current sense resistors and power integrity
> 
> If the resistor feeds a power plane (even a relatively small one) that
is
> decoupled with the correct capacitors this can work well. Without the
> power
> plane the resistor (say it's 1206 SMD) will add 2 nH in series with
the
> decoupling capacitor(s). All of this can be easily modeled in SPICE,
> including the power plane.
>     Dave Cuthbert
> 
> On Fri, Aug 22, 2008 at 12:51 PM, Mikhail Matusov
> <matusov@xxxxxxxxxxxx>wrote:
> 
> > Hi all,
> >
> > Is that a really bad idea to insert a small current sensing
resistor,
> e.g.
> > 3
> > mOhm, followed by a bulk capacitor in each power rail of a let's say
a
> DSP
> > or a FPGA chip to be able to measure its power consumption?
> >
> >
> > Thanks,
> > =======================
> > Mikhail Matusov
> > Senior Hardware Design Engineer
> > Square Peg Communications
> > Tel.: +1 (613) 271-0044 ext.231
> > Fax: +1 (613) 271-3007
> > http://www.squarepeg.ca
> >
> >
> > ------------------------------------------------------------------
> > 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:
> > http://www.freelists.org/webpage/si-list
> >
> > For help:
> > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> >
> >
> > List technical documents are available at:
> >                http://www.si-list.net
> >
> > List archives are viewable at:
> >                http://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:
> http://www.freelists.org/webpage/si-list
> 
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> 
> 
> List technical documents are available at:
>                 http://www.si-list.net
> 
> List archives are viewable at:
>               http://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
> 
> 


This email and any attachments are intended for the sole use of the named 
recipient(s) and contain(s) confidential information that may be proprietary, 
privileged or copyrighted under applicable law. If you are not the intended 
recipient, do not read, copy, or forward this email message or any attachments. 
Delete this email message and any attachments immediately.


------------------------------------------------------------------
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:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                http://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: