[IBIS-Users] RE: IBIS Model-Capacitance

Lakshmi,

Thank you for your interest in IBIS! Definitions of "Cin" may vary from datasheet to datasheet, so please consult the text of your specific sheets of interest for details. In general, "Cin" often refers to the total capacitance "seen" by a signal at the pin of the device and may include buffer effects.

From an IBIS perspective, the three quantities you mention can be defined as follows:

C_pin: the capacitive portion of the package model lumped RLC network associated with a particular pin in an IBIS [Pin] list; this value should not include buffer effects

C_pkg: the capacitive portion of the package model lumped RLC network associated, through the [Package] keyword, by default with all pins of an IBIS [Component]; this value should not include buffer effects and is overridden by C_pin, if C_pin is used

C_comp: the total capacitance of a buffer alone from the pad "looking into" the device, not including package effects; C_comp is found under the [Model] keyword

I hope this helps!

- Michael Mirmak
  Intel Corp.
  Chair, EIA IBIS Open Forum

-----Original Message-----
From: owner-ibis-info@eda.org [mailto:owner-ibis-info@eda.org] On Behalf Of Ramalakshmi
Sent: Sunday, October 17, 2004 10:07 PM
To: ibis-info@eda.org; ibis-users@eda.org
Subject: IBIS Model-Capacitance

Hi

Could you please clarify the relation between the Capacitance Cin value
found in datasheet and the various components Cpkg, Cpin, Ccomp in the ibis
model?

Thanks,
Lakshmi

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Received on Mon, 18 Oct 2004 08:44:56 -0700