How can I simulate open drain outputs using IBIS models? - How can I simulate open drain outputs using IBIS models? Description The general purpose I/O IBIS models provided by Altera can be modified to simulate open drain behavior. Before making modifications, you should save a copy of the IBIS file for the device or design that you are using. Follow the instructions below: 1. Locate the model or models you wish to modify in the .ibs file. 2. Change the Model_type from "I/O" to "I/O_open_drain" under the [Model] keyword section. 3. Delete the [Pullup] keyword and all of the data in the [Pullup] section. 4. Remove the rising falling waveform data for V_fixture = 0 5. Save the file. Related Articles How many sets of I/V data should I have in an IBIS model if the I/O buffer is an open-drain buffer? Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['novalue'] novalue novalue ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']