I am currently designing a battery powered IoT device, which maximum voltage is 3.3V. When it comes to battery choice, the CR2032 (3V) is totally fine, but its capacity is only 250mAh. How can I power my circuit from single 18650 Li-ion cell? The problem is that this battery can achieve 4.2V when fully charged. What would be the basic circuit and which voltage regulator to choose? I currently ordered SPX3819. I am afraid it will discharge my battery faster then NRF24l01 and ATtiny84 attached to it.
Some companies sell 1uA standby_current LDOs. Is 1Ua low enough?
Even those LDOs will have lots of random output noise, because the internal voltage dividers will have 10,000,000 ohm values although in a slow feedback loop (not much charge available to operate the big onchip power FET quickly).