Subject: [IBIS-Users] FW: Modelling an open drain driver
From: Henrik G. Madsen (hgm@vitesse.com)
Date: Thu Nov 21 2002 - 04:30:23 PST
Sorry, I managed to send the mail before I had finished the question
/Henrik
-----Original Message-----
From: Henrik G. Madsen
Sent: 21. november 2002 13:20
To: ibis-users@eda.org
Subject: Modelling an open drain driver
Hey
I'm trying to make an IBIS model (from SPICE) for an open drain driver.
The driver is powered from 2.5V and the Vpullup is either 2.5V or 3.3V.
I have tried to sketch the end user application below
___Vpullup
|
|
/
\ Rpullup __________
OD driver / | |
\ ____________ | |
______.___|____| 60 ohm |_____| Receiver |
| |____________| | |
_| | |
-|_ |__________|
|
|
|__ VSS
|
-----Driver---|-----------normal use circuit--------------
1)
I'm in doubt how to write the S2IBIS setup file (.s2i) for an OD driver.
I know that I should use the 'Open_sink' modeltype, but how should I define the rising and falling waveforms.
I would assume that R_fixture = 60 ohm and V_fixture = Vpullup
Moreover I imagine that I should only do the falling waveform and not the rising, which would be controlled by the external pullup resistor.
2)
Additionally it is possible to include both cases in the same model, i.e. Vpullup equals either 2.5V or 3.3V
and would a simulator be able to select the right waveforms to use?
_____________________________________
Henrik G Madsen
Sr. HW Engineer
Vitesse Semiconductor Corporation A/S
Ethernet Products Division
Hoerkaer 16, DK-2730 Herlev, DENMARK
Direct: +45 4485 5920
Phone: +45 4485 5900, Fax: +45 4485 5901
mail: hgm@vitesse.com
web: http://www.vitesse.com
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