PawBuddy

Another session of blank stares into a datasheet.
First was the VBAT to 3V3 conversion, my first thought was the tps73020 because it’s super common in a lot of mesh builds. But even thought it’s alright it could be a bit smaller. We don’t need a stable 3V3 because the stm chip can do as low of 1.8V and 2.4V while vref and ADCs are active.
So I went with a buck topology that also has 100% duty.
UVLO is realized by a ti power management IC.
Gemini helped me a bunch with choosing the right components.

After that I need some kind of chager IC, it would be nice if the charger could also other chemistries, but I have only found one IC that would work great but that one wasn’t easily accessible on mouser so I’ve went with a LiIon only, which is fine for at least this devboard prototype.

And started work on the peripheral page.

Allright so this almost 6hr session was me just staring into a datasheet lol. And I still doesn’t understand the STM chip all that much
So I’ve reverted to theft I mean I took inspo from other implementations of this chip.

After that I’ve started thinking about the USB to UART convertor.
My first thought was the cheap ch340 IC but after finding that it isn’t that available online, I’ve went with the CP2102N which also has good driver support.

And also the converter is only going to be powered with just the USB to conserve powah.