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Altera_Forum's avatar
Altera_Forum
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18 years ago

Default drive strengths for Stratix III and Cyclone III

Note that Stratix III and Cyclone III default drive strengths on most I/O standards are set to OCT Rs for better signal integrity. On previous families they were set to max drive strength for best pe...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

OCT Rs is the series on-chip termination setting. It gives a drive strength so that the output impedance of the buffer is close to 50ohms. This reduced overshoot, etc, making signal integrity better. The actual drive strengths vary depending on IO standard. You can calculate the OCT Rs drive strength for a given IO standard by using the I-V curve from the IBIS model.