[SI-LIST] Re: IBIS min, typ and max. values

From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
To: "'Hermann Ruckerbauer'" <hermann.ruckerbauer@xxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
Date: Tue, 25 May 2010 13:44:14 -0700
Hermann

The typ, min and max entries are supposed to correspond to the magnitude of
the entries in most cases.  For example the powerclamp reference voltage
would be 3.3 3.0 3.6 where 3.3 is the typical, 3.0 is the minimum and 3.6 is
the maximum.  But things get confusing to some and they try to place the
temperature in the typ/min/max order that is not numeric but corresponds to
the conditions of the corners.  For example for CMOS ( but not a bipolar
process) the typ corner is 25C, 3.3V and typical process.  The minimum
corner or the corner where you see the slowest edge and weakest IV curves if
high temp, low voltage and slow/weak process or 125C, 3.0V and slow/weak
process.  Likewise the max corner is -55C, 3.6V and strong/fast corner.  So
some people want to place the temperature in the 25 125 -55 order and others
want to place them in the 25 -55 125 order.

The spec calls out how to use these parameters.  There should not be two
values of 125 for temperature, that looks like an error.

Regards,

Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
503-430-1285 FAX
tom@xxxxxxxxxxxxx
www.teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827 

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Hermann Ruckerbauer
Sent: Tuesday, May 25, 2010 1:37 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] IBIS min, typ and max. values

Hello *,

I hope somebody can help me with interpreting some things in an IBIS file
I'm just working with an IBIS file where the min, typ, max values are
arranged in the following way:

                                       typ                
min                 max

C_comp                       0.284pF             0.409pF             0.264pF
[Voltage Range]              1.200V              1.100V              1.300V
[Temperature Range]          25                  125                 125

The C_comp min is the largest value and the Temperature is in there
twice with 125C.
The same order is used for RAC and CAC for a terminator (largest value
in the min column)


e. g. in a Micron IBIS file is even some comment on having 0C as max.
temperature :

| Junction Temperature (Ambient temp is 25C typ, 85C min, 0C max)
|                                       typ                 min        
           max     
[Temperature Range]        40.0               100.0                 0.0

Regarding C_comp the Micron model lists it in the different order:
|                                    typ                   
min                     
max                                                           
C_comp                      2.466pF             2.316pF             2.616pF

In the IBIS spec I found the comment that C_comp is independent of
fabrication process and therefore to generate worst case it can make
sense to use the largest C_comp for slow process ==> in the min column.
Basically this makes sense to me, but does it then make sense to use the
smalles C_comp value in the min column  ?

So my questions would be:
Is there any common usage of the min column regarding parameters like
C_Comp, RAC, CAC (and maybe ohters) ?
Usually I would expect low temperature for fast devices, so having 0C in
the max column make sense, but does it make sense to have 125C in min
and max column ?

Any feedback is highly appreciated!

Thanks and regards

Hermann

EKH - EyeKnowHow
Hermann Ruckerbauer
www.EyeKnowHow.de
Hermann.Ruckerbauer@xxxxxxxxxxxxx
Veilchenstrasse 1
94554 Moos
Tel.:   +49 (0)9938 / 902 083
Mobile: +49 (0)176  / 787 787 77
Fax:    +49 (0)3212 / 121 9008


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References:
- [SI-LIST] SI opening at NetLogic Microsystems
  - From: Margaret Wang
- [SI-LIST] IBIS min, typ and max. values
  - From: Hermann Ruckerbauer
[SI-LIST] Re: IBIS min, typ and max. values

Other related posts:
