I am designing a board that will need 3.3 V, 2.8 V, 1.5 V, and ideally 1.2 V rails. The board will be powered by a 12 V power supply so for stepping from 12 V to 3.3 V I am planning on using a buck converter for efficiency, but since stepping from 3.3 V to 2.8 V is much smaller, I was thinking about just using a linear voltage regulator, and then chaining regulators to get to 1.2 V.
Whatever power distribution I go with, I need it to be compact, cheap, and efficient. Is it smarter to use multiple buck converters, multiple linear regulators, or a mix of both?
Ideally, I would find some part that has all 4 rails in a convenient SMD package, but I haven't found that part yet.