I have a system running at 3.3v requiring 70mA at most times and 220mA at peaks (roughly 20% of the time). I'd like to find a way to power this from coin cell batteries or other small portable source. Battery life needs to be about 1h but size should be as small as possible (which is why something like AA's won't work)
I see a couple ways of doing this:
- Put several 4 button cell alkalines in series and use an LDO voltage regulator to get the voltage down to 3.3v
- Use ~3 alkaline button cells in parallel and boost the voltage using TPS61200 (datasheet: http://www.ti.com/lit/ds/slvs577c/slvs577c.pdf). Schematic similar to this: http://www.sparkfun.com/datasheets/Prototyping/LiPower-v11.pdf
- Same as the previous one but with the batteries in series. The TPS61200 will regulate down to 3.3v when the batteries are full and boost to 3.3v in the end
- Same as above but with a single cell LiPo battery. I'd like to stick to easy to find batteries though. Rechargeability is not important.
- Use 3 AAA batteries in series with a voltage regulator (size is a bit of a concern..)
In terms of efficiency does it matter if i put 3 alkaline batteries in series or parallel (TPS61200 can work down to 0.3v with a 0.6v startup voltage)?
So far i tried using a CR2032 lithium battery with NCP1450A (http://www.onsemi.com/pub_link/Collateral/NCP1450-D.PDF) to boost it to 3.3v but the output voltage stays around 1.4v. It may be that something else is wrong in my circuit but from what i understand the battery can't provide enough current anyway (4mA continuous, 15mA peaks) so there's no point continuing that path?