Altoids Power Supply

2017

A little idea I had about a portable battery powered supply. It has 3.3v, 5v, and 12v rails and integrated battery charging. RevA is done and built. Haven't tested it at all and I haven't written any firmware (it uses an attiny45 to handle some battery info). I picked the Altoids tin form factor because I figured that's what you were supposed to do, but if I do a revB it'll be a different form factor.

Layout of the Altoids PSU

Revision A Update

2019-01

So after about a year of it sitting in my backpack, I finally got around to testing it.

Surprise surprise, it didn't work.

I'm not sure why, I don't really feel that spending a large amount of time debugging a project I will likely never really use is the best use of my time. I get approximately 900mV on the output of the charger/USB chip, but I'm not sure what that means. I did make quite a few mistakes around the board so that's probably why.

I've learned quite a bit since I did this project. Mostly I learned to actually take my time with things and verify instead of trying to finish it as quickly as possible (this project should have taken more than 4 hours to do the shematic and layout). Also silkscreen documentation is important for the useability of something, where it needs to take into account the components. One other major takeaway is to do some passive component searching before you specify footprints. I wasn't able to find the required components in a few of the footprints I used, which caused some major assembly issues.

Assembled design

Future Work

IF I was to revisit this project, I would probably modularize it. I would probably have a go at designing my own configurable buck/boost converter using a microcontroller. That would then just hookup to the output of the same battery charger IC I used. The main theme is I would design these two seperately and test them seperately and then integrate them at the end if I felt like finishing the project.

PCB Files GitHub Link