Adafruit 1903

PowerBoost 500 Basic - 5V USB Boost @ 500mA from 1.8V+ DESCRIPTION
PowerBoost is the perfect power supply for your portable project! This little DC/DC boost converter module can run from 1.8V batteries or higher, and convert that voltage to 5.2V DC for running your 5V projects. Like our popular 5V 1A USB wall adapter, we tweaked the output to be 5.2V instead of a straight-up 5.0V so that there's a little bit of 'headroom' long cables, high draw, the addition of a diode on the output if you wish, etc. The 5.2V is safe for all 5V-powered electronics like Arduino, Raspberry Pi, or Beagle Bone while preventing icky brown-outs during high current draw because of USB cable resistance.

The PowerBoost 500 has at the heart a TPS61090 boost converter from TI. This boost converter chip has some really nice extras such as low battery detection, 2A internal switch, synchronous conversion, excellent efficiency, and 700KHz high-frequency operation. Check out these specs!