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 *************************************************************************** Always do right. This will gratify some people and astonish the rest. .... Mark Twain "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 > > > > > > > > ------------------------------------------------------------------ > > To unsubscribe from si-list: > > si-list-request@xxxx with 'unsubscribe' in the Subject field > > > > or to administer your membership from a web page, go to: > > //www.freelists.org/webpage/si-list > > > > For help: > > si-list-request@xxxx with 'help' in the Subject field > > > > List archives are viewable at: > > //www.freelists.org/archives/si-list > > or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages > > Old (prior to June 6, 2001) list archives are viewable at: > > http://www.qsl.net/wb6tpu > > > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxx with 'help' in the Subject field > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu