I'm attempting to develop a power supply for a system that needs 1.2V, 3.3V, and 5V from mains 120V 60Hz. I have never ran into needing all three at once and am curious if anyone knows of a more simple/smaller solution then what I'm proposing.
I'm considering using a buck regulator SMPS to obtain the 5V from 120V and 2 linear regulators. First regulator to step the 5V down to 3.3V and then the next one to step down the 3.3V to 1.2V. Being that size is a big issue I'm up to hear some ideas.
Side note: The total current draw of 3.3V is no more then 1.0A and total current draw of 1.2V is no more then 1.0A.
Using some of the comments and answers, I went out and found this IC BA3259HFP. Any thoughts? It appears to solve the issue with 5 pins, 3 caps and 2 resistors.