Re: IBIS BIRD64.1 - Package Model Selector

Mike:

Great job in capturing the issues discussed at the October 6, 2000 meeting.
Could you actually prepare BIRD64.2 for distribution on the IBIS reflector?

This would involve inserting your proposed text changes as they would
appear in the final document, adding reasons and comments to the ANALYSIS
PATH ... section and listing yourself as a co-author and adding the
new date to the list of dates when you send it out. We may have to
respond to comments on your proposed improvements issue additional
revisions of BIRD64.2 prior to a scheduled vote at the next meeting.

Thanks,
Bob Ross
Mentor Graphics

Mike LaBonte wrote:
>
> To follow up on my comments on BIRD 64.1 at the IBIS forum
> teleconference today, I would like to propose that:
>
> 1) The BIRD should declare scoping requirements
> It is not stated where the [Package Model Selector] can appear
> in an IBIS file, and to which [Component] it applies. We might
> add a paragraph like:
>
> #############################################################
> Each [Package Model Selector] keyword specifies the set of
> package models for only one component, which is given by
> the previous [Component] keyword. The [Package Model Selector]
> keyword may not appear before the first [Component] keyword
> in an IBIS file.
> #############################################################
>
> 2) [Package Model] and [Package Model Selector] are mutually exclusive
> When [Package Model Selector] is used, [Package Model] makes
> no sense. The [Package Model] keyword *could* give the name of
> the default package model, but I agree with the idea of the
> default as specified by the first [Package Model Selector] value.
> We might add a paragraph like:
>
> #############################################################
> The appearance of the [Package Model Selector] keyword after
> a [Component] keyword overrides any [Package Model] keyword
> that may appear often the same [Component] keyword.
> #############################################################
>
> Concerning Roy Leventhal's comment on how [Package Model Selector]
> might be used, I see 2 issues:
>
> A) The assignable package models must have the same pinouts.
> Although some die can be shipped in various packages, the physical
> pin arrangements are often altered to accommodate each package.
> The designs that incorporate these parts are routed differently.
> A simulation tool might not be able to iterate through the
> set of package models while maintaining consistency with the
> design at hand. A part with both plastic and ceramic packages,
> on the other hand, might be easily accommodated, assuming the
> pinouts are the same.
>
> B) A fully specified part name encompasses the package type.
> Some companies may have model naming policies that require
> model names to match manufacturer part numbers. But this
> makes the model package-specific. A good example is ceramic
> vs. plastic, where the manufacturer part numbers include
> different package suffixes. In fact, the design environment
> may count on package-specific model names, to assist with
> associating parts with models. In this case, "radically"
> different package models should not be assigned. But I don't
> see this as a reason to not *allow* radically different package
> models in a [Package Model Selector] list.
>
> Mike LaBonte
> Cadence Design Systems
>
 
Received on Fri Oct 6 14:59:10 2000