3.3V Input High Power Step-Down Switching Regulator Controller

The LTC1649 is a high power, high efficiency switching regulator controller optimized for use with very low supply voltages. It operates from 2.7V to 5V input, and provides a regulated output voltage from 1.26V to 2.5V at up to 20A load current. A typical 3.3V to 2.5V application features efficiency above 90% from 1A to 10A load. The LTC1649 uses a pair of standard 5V logic-level N-channel external MOSFETs, eliminating the need for expensive P-channel or super-low-threshold devices.

The LTC1649 shares its internal switching architecture with the LTC1430, and features the same ±1% line, load and temperature regulation characteristics. Current limit is user-adjustable without requiring an external low-value sense resistor. The LTC1649 uses a 200kHz switching frequency and voltage mode control, minimizing external component count and size. Shutdown mode drops the quiescent current to below 10µA.

The LTC1649 is available in the 16-pin narrow SO package.

Applications

* 3.3V Input Power Supply for Low Voltage Microprocessors and Logic

* Low Input Voltage Power Supplies

* High Power, Low Voltage Regulators

* Local Regulation for Multiple Voltage Distributed Power Systems

* High Power 3.3V to 1.XV-2.XV Switching Regulator Controller: Up to 20A Output

* All N-Channel External MOSFETs

* Provides 5V MOSFET Gate Drive with 3.3V Input

* Constant Frequency Operation Minimizes Inductor Size

* Excellent Output Regulation: ±1% Over Line, Load and Temperature Variations

* High Efficiency: Over 90% Possible

* No Low-Value Sense Resistor Needed

* Available in 16-Lead SO Package