khooartist, designer, educator
The ESP12x LiPo Charge+ 3.3V Buck/Boost board, along with its companion programmer board, was designed to address a particular gap in the electronic prototyping community: if you wanted to make a wireless, battery-powered ESP-12x based electronic project, you often have to work with big, bulky frankenstein setups. This design was borne out of a need to have a cheap, tiny but still accessible and hackable electronic prototyping system for my PhD research. The ESP8266 family of boards are great for their price, but also consequently unfriendly for use (beyond breadboard-style prototyping):
* Yes, this is a contentious claim. Conventional wisdom advises that LiPo batteries not be over-drained. By 'over-drained', this would mean discharging the battery to around 2.8V, the voltage where LiPos with built-in protection circuits will cutoff. The concept is that by using a low dropout linear 3.3V regulator, the LiPo battery will discharge from 4.2V down to about 3.4V, and always maintain quite a decent minimum charge. Using a buck/boost regulator, on the other hand, utilises battery capacity more fully, at the potential risk of over-drain. However, if using a LiPo battery from a reputable source that has the built-in protection circuitry, the only thing to be concerned about would be the possibly reduced lifespan of a battery that's allowed to discharge too much. More tests with this will reveal real-world answers.
My design uses the compact MCP73831 lipo charger IC, and couples it with the TPS63060 buck/boost IC-based solution from Pololu. Everything is stacked and crammed into a tight arrangement. The board has the following features:
Schematics and details will be posted on my Github repository, once more findings are confirmed.