I am developing a system that I would prefer to use mains power of ~220-240V . I would need this to feed 5V and/or 3.3V circuitry and IC chips running on 0.8V-1.5V sucking up as much as 10A per chip for a total power of anywhere between 500W to 1.5KW. I need an economic/cost-effective way to do this. Any suggestions? Can all be done on one circuit board, or is a separate transformer a must?

 

Wow, you really need 300A at 5V (1500W)? That won't be cheap.

You'll need an isolation transformer or a SMPS for isolation in order to discuss this circuit here (no mains direct).