[SI-LIST] Re: source-termination and daisy chain question
- From: Eric Goodill <ericg@xxxxxxxxxxx>
- Date: Tue, 03 Jul 2007 09:46:36 -0700
Han,
While I can't offer any immediate insight into your question, it's not
always true that a source-terminated driver can't drive a daisy chain.
Whoa--too many negatives. Let's say it's sometimes possible for a
source-terminated driver to drive a daisy chain. Better.
What has worked in the past is to use a smaller value than optimal for
the source-termination resistor. This provides a larger incident wave
which can cross the receivers' switching threshold with margin. However,
the non-optimal resistor value does not properly terminate the reflected
wave, so the T-line rings more than normal. As long as the reflections
do not cross any thresholds, you're okay. It's just a matter of analysis
and margins, and if you're comfortable with the result, it can work.
-Eric
Han Li wrote:
> Hi everyone,
> It seems a simple question,But I still have something i
> cannot completly understand.
> A daisy chain is often used in multidrop topology, which need an
> end-termination. And, source-termination doesnot work properly in
> daisy chain,because the device in the middle of the chain would get a
> plateau;using source-termination, all load should be at the end of the
> line.
> So, in a design , i should figure out minimul distance between,
> say two receivers. In other words, I should decide beyond what distance
> between two
> receivers , source-termination should not be used, and this topology
> can be named a daisy chain?
> Could anyone provide a deeper explanation? Thanks a lot!
> ---- ------ -------
> Driver---------revceiver_1-----------------------receiver_2
> ---- ------- --------
> |-------------distance---------|
>
-- Binary/unsupported file stripped by Ecartis --
-- Type: text/x-vcard
-- File: ericg.vcf
------------------------------------------------------------------
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 technical documents are available at:
http://www.si-list.net
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:
