Subject: RE: ibis
From: john austin (john_austinus@yahoo.com)
Date: Sat Sep 22 2001 - 18:28:43 PDT
Thank You Tom.
--- "Dagostino, Tom" <tom_dagostino@mentorg.com>
wrote:
> Going from a released spec, one that a semiconductor
> manufacturer will send out will lead you to a much
> weaker model than the actual silicon. For example a
> typical part will have a Vol of 0.4V at 8 mA. In
> reality that driver will be 3 to 5 times stronger,
> 24 to 40 mA at 0.4V. The same applies to Voh. Most
> semiconductor datasheets do not specify rise and
> fall times so you will have to guess a transition
> time. You cannot just look at the underlying
> process used and make a guess because there may be
> structures in the output that control the slew rate.
> If you have rise and fall time specs in the
> datasheet they are likely to be accurate.
>
> You will also need to know if there is a power clamp
> in the device.
>
> For inputs the major items are what clamps and
> Ccomp. The rest of the data can be pulled from the
> datasheet.
>
> Your best bet is to find another part from that
> manufacturer's process and copy that model assuming
> you can find one with the same output buffer used.
> If you have a sample you can make some measurements
> if you have power supplies, a high speed scope and
> some means of measuring the IV characteristics.
>
> Tom Dagostino
> Modeling Manager
> Mentor Graphics Corp.
> SAE
> tom_dagostino@mentor.com
> 503-685-1613
>
>
> -----Original Message-----
> From: john austin [mailto:john_austinus@yahoo.com]
> Sent: Tuesday, September 18, 2001 8:58 AM
> To: Adam.Tambone@fairchildsemi.com
> Cc: ibis-users@eda.org
> Subject: Re: ibis
>
>
> I have spec which specify the AC, DC requirement.
> The specs contain V/I curves pullup & pulldown.
> Also,
> the references curves of the pullup and pulldown.
>
> I am looking to write an approximate behavioral
> model
> for it. So I want to know what equations or
> portions
> of the specs I need to pay attention to, to create
> V/I
> tables, rising & falling waveforms.
>
> I have some idea on how to proceed( based on other
> IBIS models) but still I wanted to see a methodology
> or guidelines already used by an expert.
>
> Thanks
>
> --- Adam.Tambone@fairchildsemi.com wrote:
> >
> > John, could you be more specific?
> >
> > Adam
> >
> >
> >
> >
> >
> >
> > john austin <john_austinus@yahoo.com>@eda.org on
> > 09/17/2001 07:11:34 PM
> >
> > Sent by: owner-ibis-users@eda.org
> >
> >
> > To: ibis-users@eda.org
> > cc:
> >
> > Subject: ibis
> >
> >
> > If I want to create a behavioral model out of a
> > spec.
> > Could you please let me know what I should watch
> > for?
> > Also, if there is any documents or paper out there
> > that facilitate the task?
> >
> > Thanks
> >
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This archive was generated by hypermail 2b28 : Sat Sep 22 2001 - 18:48:52 PDT