[SI-LIST] Re: input capacitance representation in IBIS

Hi all:

 Isn't this why they make provisions top provide Min, Typ, and Max values? I
know that vendors rarely use these fields though; they usually give one
number, but you could fix the file to be more realistic.

Regards,

Matt

-----Original Message-----
From: Ravinder Ajmani [mailto:ajmani@xxxxxxxxxx]
Sent: Thursday, October 24, 2002 1:29 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: input capacitance representation in IBIS




The capacitance specified in the datasheet is generally the worst-case
(highest) input capacitance one may encounter in that family of ICs, and
will always be higher than the C_pkg and C_comp specified in the IBIS
models.  Same is true for practically all other parameters in the
datasheet.   One of the most annoying parameters is the Rise Time.
Datasheet specifies maximum rise time, whereas the typical rise time may be
much lower, causing numerous headaches to EMI and SI engineers.

Regards, Ravinder
PCB Development and Design Department
IBM Corporation
Email: ajmani@xxxxxxxxxx
***************************************************************************
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                      "SUDHEER"

                      <sudheerbs@rediff        To:
si-list@xxxxxxxxxxxxx                            
                      mail.com>                cc:

                      Sent by:                 Subject:  [SI-LIST] Re: input
capacitance representation   
                      si-list-bounce@fr         in IBIS

                      eelists.org

 

 

                      10/24/2002 02:27

                      AM

                      Please respond to

                      sudheerbs

 

 





The 1pf is the sum of C_pkg and C_comp in the IBIS model   and the 3pf
is the input capacitance  specified in the Datasheet .
I have seen this kind of difference  for  many IC's eventhough the
ibis  models have been provided by IC Vendor's Only .


Thanks and Regards
SUDHEER

sudheer@xxxxxxxxxxxx

--- In si-list@xxxx, "PRIEUR, Olivier" <Olivier.PRIEUR@xxxx> wrote:
>
> Is it just a difference between a typical value (~1pF) and a max
value (3pF)
> in the datasheet ?
>
>
> OP
>
> > -----Original Message-----
> > From: SUDHEER [mailto:sudheerbs@xxxx]
> > Sent: Tuesday, October 22, 2002 1:41 PM
> > To: si-list@xxxx
> > Subject: [SI-LIST] input capacitance representation in IBIS
> >
> >
> >
> > Dear SI Gurus
> >
> > I have a quection regarding the input capacitance  representation
> > in ibis models .Is there any parameter other than C_pkg and C_comp
> > in ibis model to represent the input capacitance ?
> > If not  then the sum of input c_pkg and C_comp should be
> > equal to the
> > input capacitance given in the datasheet ?  I have seen this  kind
of
> > difference in
> > many ibis models/data sheets .Can anyone assist me regarding this
.
> >
> > For example take 74abt04(philips) ic,  here ~1pf in ibis to 3pf in
> > datasheet
> >
> > I have to do EMI analysis of an High speed board , I have attached
the
> > availible
> > IBIS models  but i dont have ibis models for analog IC's , i have
> > pspice models  but my
> > simulator will not accept pspice models. How to proceed now ?
These
> > devices are
> > availible from many years (lm7805 ,lm7812), does anyone having
ibis
> > models for these
> > devices .I am using Specctraquest SI expert
> >
> >
> > Regards
> > SUDHEER
> >
> > sudheer@xxxx
> >
> >
> >
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