I have tested this chip myself and I was quite surprised by the fact that it can operate at such low voltage! The Microchip MCP1640 is a 0.65V Start-up 0.35V Operating Synchronous Boost Regulator with True Output Disconnect or Input/Output Bypass Option. It has an adjustable output voltage of 2 to 5.5V and up to 350mA of current. The chip has a very small footprint and requires minimum external components. Its very well suited for portable products operated on one or two AA/AAA batteries or coin cells.