PGCPSU / Small lithium battery charger with dual output rails

[pysco68]

PGCPSU => Pretty Good Cheap Power Supply Unit
Oh wow, I think I found a really crappy name for that side-project.

So what's this about? Last year we bought a pick and place machine to start our in-house production line and figured out that we should learn to use that machine on something that doesn't hurt financially. Especially as we were expecting to throw away a bunch of ruined board in the beginning. So we designed a small PCB using many of the footprints we were to use later on.

In an attempt to make something useful we ended up with a small-to-tiny, surprisingly good, relatively cheap to make switching mode 1S lithium battery charger with attached boost and buck stage DC/DC converters that provide 5V and 3.3V rails.

The full "features" list is:
- switching mode 1S lithium battery charger set to ~1.3A
- battery protection (over current / shortcut / over discharger / reverse polarity)
- 5V rail (at up to ~600mA)
- 3.3V rail (at up to ~800mA) with enable pin and solder-blob switch to select default EN mode
- Short circuit recovery / hickup mode on both output rails
- Can work as uninterruptible power source (can be bad for the lithium cell however as charge is maintained at > 90%)
- Small: 25x20mm
- micro USB connector or 2-pin header for power source
- 4.7V to 5.8V input
- pin headers for output rails
- JST PH 2-pin connector or solder pads for the lithium battery
- low stand-by battery drain (less than 155uA @ 2.6V battery voltage / ~400 uW)
- good efficiency (between 70% and 93% depending on load, input voltage etc, I have some plots I may upload later if anyone's into that)

Ok, cool, so what's the deal?

Well, we got the pick and place machine up and running with much less friction than we expected and have a whole bunch of these boards sitting around as well as some more panels and parts. So we're thinking about finishing the batch and selling them. So that's basically what I'm asking you guys: is anyone interested in this?

I didn't run the exact numbers but we should be able to keep the price below 10-12€ which is not crazy cheap, but not bad comparing it to a protected TP4056 plus two DC/DC converters, especially considering the space saving and the wiring mess relief.

So, what do you think?

[Cliff Matthews]

This should not be posted here.. One of moderators should likely have it moved to buysellwanted?

[pysco68]

Hi again,

just to clarify things, this is not yet a product and may well never be. We just stumbled upon that box of PCBs (like 20-25) we built about six months ago while setting up pour P&P machine during inventory. And we figured that we should ask the world if it needs such a small battery-charger-PSU thingy, as it actually turned out to be not bad at all.

I just really would like to get some feedback on if it is useful to someone.