Question on Ramp

Syed,

you wrote s2ibis2 will add 50Ohms pullup to calculate
dV/dt_f and 50Ohms pulldown to calculate dV/dt_r values.
Looking in the [RAMP] specification of 2.1 IBIS spec. there
is only a definition for a R_load sub-parameter but not for a
termination voltage. The subparameter is optional if the preferred
50Ohms load is used.
Is it obvious that the ramp values given in an IBIS model are valid
for the following conditions:

dV/dt_f: R_load pullup to VCC ?

dV/dt_r: R_load pulldown to GND ?

Regards,

Bernhard

************************************************************************************
# Dr. Bernhard Unger
# Siemens AG
# Dept. ANL A45 AM
# Otto-Hahn-Ring 6 Tel. +49-89-636-47404
# D-81730 Munich Fax. +49-89-636-44595
# Germany E-Mail Bernhard.Unger@erlm.siemens.de
************************************************************************************

----------
Von: Syed Huq[SMTP:huq@rockie.nsc.com]
Gesendet: Dienstag, 17. Juni 1997 17:36
An: ibis-users@vhdl.org; milan@indusinc.com
Betreff: Re: Question on Ramp

Milan,

s2ibis2 will add 50Ohms pullup and pulldown to calculate
dV/dt_f and dV/dt_r values. You can try changing these values
to see if your device will switch or not.

...in your .s2i file:

[Rising waveform] 500 0 NA NA NA NA NA NA NA
[Falling waveform] 500 3.3 NA NA NA NA NA NA NA

Try changing the sim time to a larger number too in your .s2i file

[sim time] 10ns

Regards,
Syed
National Semiconductor Corp.

> From owner-ibis@server.vhdl.org Mon Jun 16 17:27:09 1997
> Date: Mon, 16 Jun 1997 15:51:23 -0700 (PDT)
> From: Milan Gandhi <milan@indusinc.com>
> To: ibis-users@vhdl.org
> Subject: Question on Ramp
> X-Sun-Charset: US-ASCII
>
> Hi,
> This is our first experience with IBIS, so this might
> be a trivial issue for you experienced folks !!
>
> We are getting Ramp (dV/dt) as 0 in ibis inspite of
> providing required Voltage values.
> What should we be looking for in order to get
> correct Ramp values in Ibis model.
> We are using tools from NC university.
>
> -Thanks, Milan
>

 
Received on Wed Jun 18 10:42:14 1997