DESCRIPTION
The LTC®3728L-1 is a dual high performance step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows phase-lockable frequency of up to 550kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out of phase. The LTC3728L-1 is identical to the LTC3728L except that the LTC3728L-1 lacks the over current latchoff feature.

FEATURES
■ Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
■ OPTI-LOOP® Compensation Minimizes COUT
■ ±1.5% Output Voltage Accuracy
■ Power Good Output Voltage Indicator
■ Phase-Lockable Fixed Frequency 250kHz to 550kHz
■ Over Current Latchoff Disabled
■ Wide VIN Range: 4.5V to 28V (35V for LTC3728LI-1) Operation
■ Very Low Dropout Operation: 99% Duty Cycle
■ Adjustable Soft-Start Current Ramping
■ Foldback Output Current Limiting
■ Output Overvoltage Protection
■ Low Shutdown IQ: 20μA
■ 5V and 3.3V Standby Regulators
■ 3 Selectable Operating Modes: Constant Frequency, Burst Mode® Operation and PWM
■ 5mm × 5mm QFN and 28-Lead Narrow SSOP Packages

APPLICATIONS
■ Notebook and Palmtop Computers
■ Telecom Systems
■ Portable Instruments
■ Battery-Operated Digital Devices
■ DC Power Distribution Systems