Efficient power supply for embedded project
The NCP1402 looks a decent choice for one AA battery but with two batteries in series you might find the output voltage (3.3V) rises a bit above 3.3V on light loads. Figure 4 doesn't indicate a voltage higher than 2.5V can be used to generate 3.3V whereas fig 58 implies that for larger load currents you may be ok with an input voltage of 3V.

Figure 57 also implies (due to the graph curve) that slightly less than 3V will be OK for 3.3V output on no-load.