CMOS inputs have high impedance and don't sink current. Cyclone II has absolute maximum ratings of 25 mA source and 40 mA sink per I/O pin. In addition there's a limition of 240 mA per power pair (8 respectively 12 pins). Drive strength is programmable, the highest refers to a 24 mA class (24 mA with respective min/max Voh/Vil). This also means, that pin short circuit an dynamic switching currents are considerably larger (> 100 mA) and that the devices are not short circuit proof at high drive strengths. For more details, consult the Cyclone II hardware manual. https://www.altera.com/literature/hb/cyc2/cyc2_cii5v1_01.pdf