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I want to use Li-ion batteries to power devices that work with AA (1.5 V) batteries, to have best autonomy and to be able to recharge it easily (using a battery manager module). I had thought of a buck converter module, but in the market I cannot find one that supports 4.2-3.3V in input and output of 1.5V. How could I get 1.5V from Li-ion batteries?

JYelton
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Daniel González
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  • Easy enough to find LDO converters. And there's a range of switched bucks out there. Where have you looked? What currents are you looking at? – Puffafish Aug 26 '20 at 14:47
  • See https://electronics.stackexchange.com/q/501176/2028 – JYelton Aug 26 '20 at 14:52
  • I have searched in aliexpress, for example there are modules that can output 1.5 v, but the minimum input is 4.75 v. I am thinking of currents not greater than 100 mA. A LDO regulator is a good idea, but I'm also thinking about efficiency. – Daniel González Aug 26 '20 at 14:57
  • Measure about 2/5 of the length, then cut away the rest. (Actually don't do this). – pipe Aug 26 '20 at 15:25
  • There are modules available that do what you want: https://www.digikey.com/product-detail/en/texas-instruments/TPS8268150SIPT/296-TPS8268150SIPTCT-ND/5178867 is one example I was able to find very quickly. – Hearth Aug 26 '20 at 15:25
  • I was thinking of a module that would do the job, but I think the best alternative for low power devices is an LDO regulator, just like Puffafish says. If I needed something for higher current, the circuit Andy aka featured is pretty good. Thank you very much to all. – Daniel González Aug 26 '20 at 15:21
  • You can buy AA size Lithium rechargeable batteries with a USB input charging jack, a charging circuit for the battery cell inside and a voltage reducing circuit to output 1.5VDC. The voltage output is probably regulated. Cut one apart and use its circuits with your own battery cells. – Audioguru Dec 31 '22 at 16:23

3 Answers3

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I had thought of a \$\color{red}{\boxed{\text{buck converter}}}\$ module, but in the market I cannot find one that supports 4.2-3.3V in input and output of 1.5V.

They are fairly easy to find. For instance, this one springs to mind: -

enter image description here

If you need a little more than 500 mA at 1.5 volts then a different device is required. Here's a selection page from ADI that might be useful to you.

This one is good for 1 amp: -

enter image description here

Andy aka
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Looking on Farnell, Digikey and Mouser, I can find thousands of SMPS controller ICs which could do the job. These require effort on your part, as you'd need to design the buck converter circuit yourself.

Alternatively, assuming your current demand is low, you're not too worried about efficiencies and cost is important, and simple LDO would do the job. Again, lots of those out there on Mouser, Farenll, Digikey and so on.

Puffafish
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if you dont mind efficiencies in the 80ish range then you can get a made module in aliexpress

https://www.aliexpress.com/item/1005004663392692.html

nice bonus is the EN pin, add a comparator and you can stop module at you desired min input voltage

if you find something better please share them :")

Moti D
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