[IBIS-Users] Modelling an open drain driver


Subject: [IBIS-Users] Modelling an open drain driver
From: Henrik G. Madsen (hgm@vitesse.com)
Date: Thu Nov 21 2002 - 04:20:11 PST


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--------------
 
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 = 0V

Moreover I imagine that I should only do the falling waveform and not the rising, which would be controlled by the external pullup resistor.

_____________________________________
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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