I'm not so familiar with dc-dc converters. Here are my two questions, maybe stupid ;) 1. How to get a steady 3.3v from 3 alkaline batteries whose output goes from 4.5v to 3v? Are buck-boost converters designed do this job? 2. How to estimate the input current of a dc-dc converter given output voltage and current? I know it must be different from an LDO. Is it reasonable by estimate the total power consumption, such like: P=Vo*Io/efficiency, then Ii=P/Vi.