#760 AAA 5v Power Pack

Using an amazingly small little boost converter to make a 5V regulated power pack from a couple of AAA batteries.

Build

Notes

I picked up some 5V DC-DC Step-Up Power Modules on aliexpress for a nice price (SG$1.62 for 5), following a suggestion from @steveschnepp for making a 5V power pack from AA or AAA batteries.

These are tiny! They are built on a 10.4mm x 10.4mm PCB, gross component height 7.5mm. There are 3 connections (Vin, Vout and Ground), which can take standard 2.54mm pin headers if desired (not supplied).

module01a

Circuit Design

Specifically, it uses the ME2108A/50 SOT-89-3 packaging with 5.0V output and an operating input range of 0.9V~6.5V.

PIN	NAME	FUNCTION
1	Vss	Ground
2	Vout	Output voltage monitor, IC internal power supply
3	Lx	Switch

The module just implements the standard circuit using internal transistor as described in the datasheet:

schematic

Components:

ME2108A/50 step-up DC/DC converter
220µH inductor
SS14 - 1N5820 Small Signal Schottky Diode
5µF + 3µF capacitors? I haven’t measured the values

First Tests

It works just fine with 2x AAA batteries. Here’s a quick test on a breadboard:

bb_test_aaa_x2

As the ME2108 has an input range of 0.9V~6.5V, it also works with a single AAA battery, though the output regulation is down a little:

bb_test_aaa

A 2x AAA Power Pack

I’ve just added a switch and mounted on to a 2xAAA battery pack with globs of hot glue (for insulation as much as structural strength).

And now I have a little 5V power source powered by AAA batteries:

build01a

build01b

build01c

I really like this idea, especially for powering little embedded projects that need 5V: the smaller, cheaper and easier option than a rechargeable 18650 power pack.

Credits and References