The LTC3633 from Linear Technology is a 4MHz synchronous dual output buck regulator that incorporates a constant frequency/controlled on-time, current mode architecture.

It can deliver up to 3A of continuous output current from each channel at output voltages as low as 0.6V from a 4mm x 5mm QFN package.

The LTC3633 operates from an input voltage of 3.6V to 15V, making it suitable for dual-cell Li-Ion applications as well as 5V and 12V intermediate bus systems. Its switching frequency is user programmable from 800kHz to 4MHz, enabling the use of tiny, low cost capacitors and inductors.

Each channel of the LTC3633 uses internal switches with RDS(ON) of only 50mohm and 80mohms to deliver efficiencies as high as 96%.

The control architecture enables it to achieve duty cycles as low as 5% while maintaining switching frequencies up to 2.25MHz, making it applicable for high step-down ratio applications such as 12VIN to 1.2VOUT conversions.

For more information, see http://www.linear.com