Re: [SI-LIST] : Long bus, terminate or star?

Ron Miller (rmiller@Brocade.COM)
Wed, 24 Mar 1999 16:35:13 -0800

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Chris

If the stub capacitance at each load is negligible for 100 Mhz 1/(3 X 3ns) the series
string is ok. Also check the latency which may be a couple ns for 19 inches ~1ns/ft.

Be sure to terminate at the last load.

A star would be a lot of traces.

Ron Miller

Chris Bobek wrote:

> I have an address bus that is 75ohm, and 19" long. There are 8 loads that
> are daisy-chained along the trace. The edge from the driver (which is at
> one end) is 3ns.
>
> I was wondering if I would be better off with a star pattern, where each leg
> is short (less than 4"). Would this work and not require any termination?
>
> Thank you very much,
>
> Chris
>
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--
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017
     ==========0000-(_)0000===========
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net

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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> Chris

If the stub capacitance at each load is negligible for 100 Mhz 1/(3 X 3ns) the series
string is ok.   Also check the latency which may be a couple ns for 19 inches ~1ns/ft.

Be sure to terminate at the last load.

A star would be a lot of traces.

Ron Miller

Chris Bobek wrote:

I have an address bus that is 75ohm, and 19" long.  There are 8 loads that
are daisy-chained along the trace.  The edge from the driver (which is at
one end) is 3ns.

I was wondering if I would be better off with a star pattern, where each leg
is short (less than 4").  Would this work and not require any termination?

Thank you very much,

Chris

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.  si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

-- 
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017                 
     ==========0000-(_)0000=========== 
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net
  --------------092A88BCBF1D529676337F5E-- **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****