Subject: Re: typ outside min,max

From: Chris Rokusek <[email-masked]>
Date: Fri, 14 Nov 1997 10:35:47 -0800

Paul,

Without first de-referencing each Pullup/Pulldown and each Power
Clamp/GND Clamp from its "Reference voltage" and then summing them
together appropriately I don't think a check is possible.  For example,
it is possible (although perhaps not desirable) that a max and min
Pullup curve use the same Voltage reference value (i.e. 5V) however the
zero current crossing point on the voltage axis when looking at the raw
curves (w/o de-referencing) differs by .5V.  Or maybe the curves are
EXACTLY the same with just different reference voltages.  A single
Pullup/Pulldown curve cannot be looked at in isolation unless the shunts
curve currents are 0.

Its also not clear to me that the shunt regions of the pullup/pulldown
will follow min < typ < max rule (even if absolute values are used)--SEE
YOUR EXAMPLE for voltages < 0v.  I expect that after the shunts were
added back in to your example it might be somewhat clearer.

My first impulse is that even if the curves are added appropriately I
would expect many exceptions to occur--esp. near the 0-current crossing
points and in the shunt regions.  Possible in the middle of the
operating range a single check might work most of the time.

Chris Rokusek
Viewlogic ADG

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From: Kellee Crisafulli <[email-masked]>
Date: Fri, 14 Nov 1997 13:29:19 -0800

Hi Chris,

>Pullup/Pulldown curve cannot be looked at in isolation unless the shunts
Chris, didn't you already write code to do the above  for the new
IBIS golden parser?  If so could it be re-used.

>operating range a single check might work most of the time.
I agree, this could be limited to currents greater than |100ua|  (magnitude)
and it would certainly need to be a warning not an error.  Also it should probably
just count the number of them and report the total number of min's or max's that
are larger/smaller than typ.  This way it wouldn't show 100 entries all off by 1fA
Also the test should allow something like +-10uA around typ. as ok.

Then again this is getting rather complex.....
(keep it simple may apply) -> don't add a new test

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Have a great day...
Kellee Crisafulli at HyperLynx
[email-masked]	http://www.hyperlynx.com
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