This breakout is based on the STM326601 on/off controller which allows for the use of a single button to power and control any project. This keeps the UI simplistic saves space.
The first button press will wake up the controller and enable a 3.3V output. Any button presses after that will trigger an interrupt signal and a long button press will disable the 3.3V output and put the controller back to sleep.
This breakout can handle all your power needs with a 500mA 3.3V output, standard JST battery connector, 100mA single cell battery charger and battery level indication.