Chapter · Power and protection
Regulating a rail
A lithium cell starts above 3.3 V and finishes below it. One chip bucks, then boosts, and holds the rail through the crossing, at 20 µA while the board sleeps.
Start at 13 and read down — the order is the order things get easier in. Or take the one with your part in it; every article stands on its own, and links back to whatever it needs.