Description
Due to a problem in the Quartus® II software version 11.1 SP2 and earlier, there is no assignement for Arria® V and Cyclone® V devices to enable the clamping diode for I/O standards where it is not enabled by default, for example 3.3-V LVCMOS.
Resolution
An assignment to enable the clamping diode for Arria V and Cyclone V devices is available beginning with the Quartus II software version 12.0.