Power switching a higher DC supply from a mcu
Depending on how much load current you need to supply the following circuit should work: -



If you need less than 2A this FET will work.

At 2A it'll dissipate about 0.3W so a little heatsinking in Cu may be advised. It's good for up to 20V but I wouldn't run it higher than 12V. Also this was the first FET I came across so there will probably be cheaper devices.