This 5 Volt 2 Amp power supply runs off a single Li-Ion cell and is charged via micro USB. There are 3 versions of this power supply - 1.8V, 3.3V, and 5V output.
This board requires a battery to operate. Version 2 improves on this - it operates with or without a battery installed.
An ATtiny45 microcontroller handles power management. There are two LED indicators for status and battery charge level.
At idle, the board draws less than 2μA!
The boards and design files are available at www.flashcandy.us/products/little-nugget-v1