I have a slightly ambitious project for my first PCB: I want to control a wall of WS2812 LEDs from an Altera CycloneIV. The LEDs are connected to a rail carrying the 5V supply, at up to 350W, and expect their control signals at 5V as well.
For the FPGA, I need 1.2V (core), 2.5V (PLL) and 3.3V (I/O).
I'm routing the I/Os (40 of them) to voltage converters to bring them up to 5V and get ESD protection.
My current approach would be a linear regulator for 3.3V, as I expect the current draw to be minimal, and there isn't much room to work with; for 2.5V and 1.2V I'd use a switching converter each and add large capacitors for stability.
For additional safety I could place reverse-facing diodes between the five voltage levels, although I'm not sure these are actually required.
Is that a viable approach, or can this be improved somehow?
Best Answer
You can generate all three rails (3.3, 2.5 and 1.2) from a single chip, the Alegro A4490: Triple Output Step-Down Switching Regulator. It is available from Digi-Key in a 20-VQFN package.
I have used this chip in several projects, and it works fine. You can run at least 2A through each output.