SparkFun COM-00674 Lithium Ion/Polymer USB Battery Charger IC – MAX1555
This handy little IC will correctly and safely charge our Lithium Polymer batteries with power from a USB port or from a DC wall adapter. Max current is limited to 300mA using an external wall supply (3.7V to 7V). Requires almost no external components and will automatically select between a DC source and USB source if both are present. Current is automatically reduced to a trickle when charging is complete.