Description
No, the current strength of an output buffer does not refer to the maximum current that the buffer is able to drive out. The current strength is what the output buffer is guaranteed to drive at the switching thresholds of an I/O standard.
For example, a 3.3V LVTTL output buffer that has a current strength setting of 4mA will drive at least 4mA of current at the minimum Voh and maximum Vol for the I/O standard.
To verify the actual current for your board topology, Altera recommends running IBIS simulations.