Demonstration circuit DC631 is a complete power solution for a USB powered device. Power is input from one of three sources, and three outputs are provided, as well as supervisory signals for a microprocessor. DC631 provides the following functions; 700mA CC/CV timer terminated charger suitable for Li-ion cells, USB power manager that insures compliance with the USB power specification, two 1.5MHz synchronous step down converters and reset and power button status outputs for interface with a microprocessor. All this functionality consumes only 225mm^2 of PCB area. Design files for this circuit board are available. Call the LTC factory.