Circuit to switch about 5W of 12V using CMOS logic inputs using N-channel MOSFET?
The FCPF400N80Z has a maximum gate threshold voltage (VGS(th)) of 4.5V, which is marginal for logic operation, but the IRLB8721PbF has a maximum threshold voltage of 2.35V. This should work decently well for even 3.3V logic provided you don't need to pass more than about 3A of current.