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From: agn@k.cs.cmu.edu.ARPA (Andreas Nowatzyk)
Newsgroups: net.arch
Subject: Re: Re: More on Metastibility
Message-ID: <591@k.cs.cmu.edu.ARPA>
Date: Thu, 10-Oct-85 23:57:14 EDT
Article-I.D.: k.591
Posted: Thu Oct 10 23:57:14 1985
Date-Received: Sun, 13-Oct-85 04:43:46 EDT
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Organization: Carnegie-Mellon University, CS/RI
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Unlike Paul Wilcox-Baker believes, the academics were far from silent
about this topic. Thomas J. Chaney (among others) fought many battles
to allert places like DEC and TI to the very existence of this problem.

The article "Measured Flip-Flop Responses to Marginal Triggering",
IEEE transactions on Computers, Vol. C-32 No. 12, Dec 1983
has a table of the data for a collection of common Flip-flops.
Ouoting said table:

                 MTBSU(20ns)       MTBSU(40ns)
  74S74           10 s               7x10**9 s      (worst case, 74-75 dated
                                                     devices)
  7474             --                10 s
  74LS74           --                0.4 s
  74F374          2x10**13           2x10**35

MTBSU is the Mean Time Between the Synchronizer events where the FF is
still Unresolved for a given synchronization time. Please look up the
article on the precise set-up conditions and how to scale the results
for a particular circuit. Talking about "Zillions" is not unreasonable
given that these figures span 35 (!) orders of magnitude.


-- 

  --  Andreas             Arpa-net:  agn@cmu-cs-k.ARPA
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