[SI-LIST] Re: source-termination and daisy chain question
- From: Terry Fox <tfox@xxxxxxxxx>
- To: jasonleehan@xxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Tue, 03 Jul 2007 07:45:00 -0700
Han,
The answer depends upon the type of signal..
If you are distributing a daisy chain multi drop clock, you need load
termination. Clocks must have a clean edge.
If you are distributing address or data which simply needs to settle prior
to the clock edge, source serial termination is fine.
Data or address lines are only required to get to the appropriate
voltage prior to the set up time.
One corner case involves a "T" connection for SDRAM memory clock. If
there are only two drops and the arms of the "T" are identical,
you can often use source serial termination. It is not the best, but it
works. I would HIGHLY recommend simulating this configuration
prior to layout and again after layout.
If I have some time later, I will do some simulations and send you the link.
TFox
tfox@xxxxxxxxx
www.siemc.com
At 11:25 PM 7/2/2007, 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---------|
>
>
>------------------------------------------------------------------
>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
>
------------------------------------------------------------------
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:
