Why does my Cyclone IV design have minimum pulse width violations related to the ALTINT_OSC megafunction?

Description

Due to a problem in the Quartus® II software versions 13.1 and earlier, the ALTINT_OSC megafunction incorrectly allows the clock to be set at 100MHz in the MegaWizard™ Plug-In Manager.
This is incorrect as maximum operating frequency is 47MHz for Cyclone® IV devices.

Resolution

To work around this problem, make the following change to the automatically generated sdc file:

from:

create_clock -name osc_clock -period 10 [get_pins {<altint instance>|cycloneiii_oscillator1|clkout}]

to:

create_clock -name osc_clock -period 25 [get_pins {<altint instance>|cycloneiii_oscillator1|clkout}]

This problem is scheduled to be fixed in a future release of the Quartus II software.