RE: [SI-LIST] : Non-standard bus termination (2nd posting)

Greim, Michael (mgreim@mc.com)
Wed, 22 Sep 1999 12:48:43 -0400

Do you have a web site for these guys. I'd like to check them out.

MG

The bounds of Time, Space or Mechanics should never stand
in the way of a perfectly good idea.......

The time is gone, The email's over, thought I'd
something more to say.........

Michael C. Greim Consulting Engineer
Mercury Computer Systems, Inc email: mgreim@mc.com
199 Riverneck Road V: 978-256-0052/x1607
Chelmsford, MA 01824-2820 F: 978-256-4778

> -----Original Message-----
> From: jrbarnes@lexmark.com [SMTP:jrbarnes@lexmark.com]
> Sent: Wednesday, September 22, 1999 10:33 AM
> To: si-list@silab.eng.sun.com
> Subject: Re: [SI-LIST] : Non-standard bus termination (2nd posting)
>
> BI Technologies has an RC6 series with up to 8 RC terminators in a 6.4mm x
> 3.2mm
> (0.252" x 0.126") 10-pad chip. The resistors can be 20 ohms to 1 megohm,
> while
> the capacitors are a maximum of 50pF in an 8-terminator part.
>
> AVX has a |Z| Chip line with up to 4 distributed resistance/capacitance
> terminators in an 0612 (0.06" x 0.012") package.
>
> Page 234 of Mark I. Montrose's book EMC and the Printed Circuit Board
> suggests that the resistance of an RC-termination match Zo of the trace,
> while R
> * C be at least twice the loaded propagation delay (round trip travel
> time) of
> the signal.
>
> John Barnes
> Advisory Engineer
> Lexmark
> International
>
>
>
>
>
> massimo.polignano%esaote.com@interlock.lexmark.com on 09/22/99 04:45:29 AM
>
> Please respond to si-list%silab.eng.sun.com@interlock.lexmark.com
>
> To: si-list%silab.eng.sun.com@interlock.lexmark.com
> cc: (bcc: John Barnes/Lex/Lexmark)
> Subject: [SI-LIST] : Non-standard bus termination (2nd posting)
>
>
>
>
>
>
>
>
> Has anybody out of there any suggestion about the following problem? (I
> think it
> is quite a common one).
>
> I?ve got a board with a non-standard bus of 34 traces. The bus drives a
> group of
> memories.
> The lenght of the bus is necessarily higher than the critical lenght
> (lcr =
> tr/2tpd): a termination could be useful. The problem: there are so many
> traces
> that one has to use too many components (34 resistors and 34 capacitors
> for AC
> parallel termination).
>
> What shall I do?
> Are there any special components (array) to terminate this type of bus?
> Shall I terminate the bus or not? (In past experience not always a
> termination
> was mandatory)
>
> Thanks for any help.
>
> m.p.
>
> ---------------------------------------------------------
> ESAOTE S.p.A. Massimo Polignano
> Research & Product Development Design Quality Control
> Via di Caciolle,15 tel:+39.055.4229402
> I- 50127 Florence fax:+39.055.4223305
> e-mail: massimo.polignano@esaote.com
>
>
>
>
>
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