Subject: RE: [IBIS-Users] FW: Modelling an open drain driver
From: Henrik G. Madsen (hgm@vitesse.com)
Date: Mon Nov 25 2002 - 00:05:16 PST
Thanks for the clarification.
Having waveforms with V_fixture = 0, creates the below ERROR message, where you are told that your endpoint is where it should be, but you are 100% off.
ERROR - Model osoc2_od: The [Rising Waveform]
with [R_fixture]=60 Ohms and [V_fixture]=0V
has TYP column DC endpoints of 0.00V and 0.00v, but
an equivalent load applied to the model's I-V tables yields
different voltages (-0.00V and 0.00V),
a difference of -100.00% and 100.00%, respectively.
/Henrik
-----Original Message-----
From: Ross, Bob [mailto:bob_ross@mentorg.com]
Sent: 23. november 2002 02:29
To: Ingraham, Andrew
Cc: Henrik G. Madsen; ibis-users@eda.org
Subject: Re: [IBIS-Users] FW: Modelling an open drain driver
Andy:
As a correction to the last statement, only V_fixture voltages
at around Vcc or above make sense for Open_drain models. There
should be no switching action when V_fixture = 0.
Bob Ross
Mentor Graphics
"Ingraham, Andrew" wrote:
>
> I wrote:
>
> > For R_fixture, using 60 ohms in parallel with Rpullup, would come
> > closer
> > to the actual circuit. Unless you intended for Rpullup to be on the
> > far
> > (receiver) end of the 60 ohm trace.
>
> I forgot to say ... you should have a waveform with V_fixture = 0V and
> another with V_fixture = Vpullup.
>
> Andy
>
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