system using Microchip’s popular - 4.5V - 6.5V from ac-dc adapter (1A) MCP73837 device for cost-sensitive applications. - 5V from USB port (100 mA/500 mA) Refer to the MCP73837/8 Data Sheet, “Advanced - 3V - 4.2V from 1-cell Li-Ion battery (950 mAh) Stand-Alone Li-Ion / Li-Polymer