15V, 4MHz, Synchronous Dual 3A Step-Down Regulator

The LTC3633 is a high efficiency, 4MHz synchronous dual output buck regulator that incorporates a unique 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 ideal 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 50mOhms and 80mOhms to deliver efficiencies as high as 96%. Its unique control architecture enables it to achieve duty cycles as low as 5% while maintaining switching frequencies as high as 2.25MHz, making it ideal for high step-down ratio applications such as 12VIN to 1.2VOUT conversions. The two channels run 180 degrees out of phase, minimizing the size of both input and output capacitance. Burst Mode® operation is used to maximize light load efficiency, requiring only 500µA at no load, making it well suited for applications demanding maximum battery run time. For applications that require the lowest possible noise, the LTC3633 can be configured to run in pulse skipping or forced continuous mode, reducing supply ripple and potential RF interference. Additional features include Power Good voltage monitors, output voltage tracking capability, independent soft-start capability for each channel and short circuit protection.