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.
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\$\begingroup\$ Use a voltage regulator. \$\endgroup\$– Andy akaCommented Apr 27, 2020 at 10:18
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\$\begingroup\$ which voltage regulator to use? I am talking about ultra low power aplication. AMS1117 will not work. SPX3819 I think has high quiscent current. \$\endgroup\$– Markiyan PyekhCommented Apr 27, 2020 at 11:50
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1\$\begingroup\$ Shopping questions are off topic because answers will quickly become outdated as new devices come along. The questions and answers on this site are intended to pass the test of time where possible. \$\endgroup\$– Andy akaCommented Apr 27, 2020 at 11:54
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\$\begingroup\$ Do you need a rechargeable cell? CR123As are the same non-rechargeable 3V chemistry of a CR2032, but 1/2 the size of an 18650 and ~1500mAh. They also have lower self discharge rates. \$\endgroup\$– SomeoneSomewhereSupportsMonicaCommented Apr 27, 2020 at 13:51
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\$\begingroup\$ CR123A is a good ideia, I have not though agout this battery. And its 3V, which excludes the LDO \$\endgroup\$– Markiyan PyekhCommented Apr 27, 2020 at 18:25
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Some companies sell 1μA standby current LDOs. Is 1μa low enough?
Even those LDOs will have lots of random output noise, because the internal voltage dividers will have 10MΩ values although in a slow feedback loop (not much charge available to operate the big on-chip power FET quickly).
Kuba hasn't forgotten Monica
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answered Apr 27, 2020 at 13:41
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\$\begingroup\$ yes, 1uA would be enough. \$\endgroup\$ Commented Apr 27, 2020 at 18:24