RE: [IBIS] package number pins

Thank you Sam,

  your presentation is really interesting.

   The pins "out of package" are not signal pins:  some are "NC" , some are "Power", others are "GND".

   In this situation, do you think this model will not have any problems?

   Or the mutual inductances/capacitances lost in this Supply pins, will produce inaccuracies?

Thank you,
Fabio




From: Sam Chitwood [mailto:chitwood@cadence.com]
Sent: Thursday, January 30, 2014 6:59 PM
To: Fabio BRINA; ibis@eda.org; ibis-users@eda.org
Subject: RE: [IBIS] package number pins

Hi Fabio,

One of my IBIS presentations covers this subject:
http://www.eda.org/ibis/summits/feb08/chitwood.pdf

To directly answer your question, x > y is correct and feasible.  Power and ground net pins are routinely shorted together on a per-net basis while creating a Matrix model.  The reasons why are covered in the presentation.  But if you have a mismatch if signal pins, that would be a problem.

Don't say "unfortunately" x > y.  It's usually a good thing!

Thanks,
Sam


From: owner-ibis@eda.org<mailto:owner-ibis@eda.org> [mailto:owner-ibis@eda.org] On Behalf Of Fabio BRINA
Sent: Thursday, January 30, 2014 5:24 AM
To: ibis@eda.org<mailto:ibis@eda.org>; ibis-users@eda.org<mailto:ibis-users@eda.org>
Subject: [IBIS] package number pins

Hello experts,

   I have an IBIS model with x pins (defined under [Pin] keyword).

   Inside this model I have a Package structure in matrix format (with [Define Package Model]).
   Here the number of pins is  y:   [Number of Pin]  y

  Usually I have  x = y ,  and all it's ok.

   In this case, unfortunately,  I have  x > y ,

   the Check Parser don't generate any Errors (or Warnings) .

   Is that correct?    Is this a feasible condition?
   That means that the  x - y  pins (out of Package) will work without parasitic elements?

   (to complete this comment I have to say that if  y > x , the Parser generate Errors, like this:
    ERROR - Pin 'A5' found in package_model 'Pack1' Pin_numbers list not found in Component 'COMP1' Pin list)


Thanks for any suggestions,
Regards,

Fabio




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