5 ms·

Thanks! They seem to have replaced the linear regulator with a switching regulator (which is more efficient) on the A+ & B+ models. I agree though, doing only

by speeq 12y ago

Thanks! They seem to have replaced the linear regulator with a switching regulator (which is more efficient) on the A+ & B+ models. I agree though, doing only one transformation would be more efficient - but I'm not sure which USB devices would work on 3.3V - it depends on the individual use-case I guess.

pflanze 12y ago
I now noticed that the NCR18650B batteries are Li-ion batteries (i.e. 2.7-3.7V range for one cell; I was thinking NiMH which are below 1.5V per cell). This may be harder to regulate to 3.3V as you can't simply choose a step-up nor step-down circuit because the source voltage crosses the target voltage during operation; I think I've seen chips that claim to do this but I don't know how efficiently[1]. You may be better off with the original plan of converting to 5V after all. [1] well, actually an inverting buck-boost converter should be fine and seems like it should be as efficient as a step-up (https://en.wikipedia.org/wiki/Buck-boost_converter https://en.wikipedia.org/wiki/Buck-boost_converter). Whatever, my lack of enough experience in that area shows.