High Efficiency, 2-Phase Synchronous Step-Down Switching Regulator

The LTC3707 is a high performance dual step-down switching regulator controller that drives N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows adjustment of the frequency up to 300kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out of phase.

OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The precision 0.8V reference and power good output indicator are compatible with future microprocessor generations, and a wide 3.5V to 30V input supply range encompasses all battery chemistries.

A RUN/SS pin for each controller provides both soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when overcurrent latchoff is disabled. Output overvoltage protection circuitry latches on the bottom MOSFET until VOUT returns to normal. The FCB mode pin can select among Burst Mode operation, constant frequency mode and continuous inductor current mode or regulate a secondary winding.

External Synchronization

LTC3707

No

LTC3707-SYNC

Yes

Applications

* Notebook and Palmtop Computers, PDAs

* Battery Chargers

* Portable Instruments

* Battery-Operated Digital Devices

* DC Power Distribution Systems

* 180° Phased Dual Controllers Reduce Required Input Capacitance and Power Supply Induced Noise

* OPTI-LOOP® Compensation Minimizes COUT

* ±1.5% Output Voltage Accuracy over Temperature

* Dual N-Channel MOSFET Synchronous Drive

* Power Good Output Voltage Monitor

* DC Programmed Fixed Frequency 150kHz to 300kHz

* Wide VIN Range: 4.5V to 28V Operation

* Very Low Dropout Operation: 99% Duty Cycle

* Adjustable Soft-Start Current Ramping