My devices are portable, battery operated, and I have typically used 9v alkaline or 2S, 3S lithium batteries and linear regulators. On the latest device, I decided to try 2-AA alkaline batteries and a 1.5A TPS61252 boost regulator producing a 3.3v output. Is is small, inexpensive (though a lot more than a LM317) and very efficient. I used TI's (Nat Semi) automated workbench to design the regulator, and I was careful to lay it out on the pcb exactly according to the suggested layout in the data sheet. I always liberally place bypass caps on all power pins. Although I used a 2 layer pcb, I used 25 mil power traces and kept them as short as possible, and I used a grounded copper pour on the bottom layer. It should have been successful, but it wasn't.
It appeared to work as advertised until I powered up the device with the incorporated Xbee radio, which draws as much as 500mA in short pulses. Then, noticed a lot of the strange intermittent malfunctions typical of power problems, all of which disappeared when I powered the 3.3v rail with my lab power supply. I spent many hours trying to track down the source of the problems, without success. Finally, I gave up and redesigned the pcb with a buck regulator and a 9v battery. This works fine, but I'm back with the 9v, which I don't like because of high cost and low power density.
I am sure some of you are using boost regulators and 2 alkaline batteries for portable devices, and I wonder whether you have encountered similar problems. Does anyone have any boost regulator recommendations. I am especially interested in using 2- Alkaline AA cells and a boost regulator to produce 3.3v because it is impossible to find an inexpensive handheld enclosure that has a battery compartment for 3-AA cells.