This little buck converter based on the TPS62827 is super handy, taking up to 5.5V input and providing a 3.3V output with up to 2A current.
It's great for supplying power to hungry 3.3V voltage circuits from a range of battery or power options. This chip provides up to 2 Amp load current across the entire input voltage range of 3.4 to 5.5V. It's not a huge range but does cover LiPoly batteries, 3 alkalines, and USB power.
Great for your portable project, Adafruit made this "pin compatible" with the LM1117-3.3V TO-220 chip so you can swap it in for better performance (90-95% efficiency!) There's also an ENable pin, tie it low to shut down the output completely.
The Adafruit TPS62827 Breakout runs at 2.2-MHz fixed-frequency. Even though the chip itself supports up to 4A, they found that 2 Amps or so was a good max to stick to for constant current draw and 3 Amps for temporary peak current draws. Adafruit did use a 2 oz copper double-layer PCB.
If you need a wider input range, check out the 3.3V output MPM3610 breakout with up to 20V input!
Comes with a fully assembled and tested breakout board. Adafruit also include header to plug it into a breadboard.