DESCRIPTION
The LTC®3728 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.
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 (36V maximum) input supply range encompasses all battery chemistries.

FEATURES
■ Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
■ OPTI-LOOP® Compensation Minimizes COUT
■ ±1% Output Voltage Accuracy
■ Power Good Output Voltage Indicator
■ Phase-Lockable Fixed Frequency 250kHz to 550kHz
■ Dual N-Channel MOSFET Synchronous Drive
■ Wide VIN Range: 3.5V to 36V Operation
■ Very Low Dropout Operation: 99% Duty Cycle
■ Adjustable Soft-Start Current Ramping
■ Foldback Output Current Limiting
■ Latched Short-Circuit Shutdown with Defeat Option
■ Output Overvoltage Protection
■ Remote Output Voltage Sense
■ Low Shutdown IQ: 20µA
■ 5V and 3.3V Regulators
■ 3 Selectable Operating Modes: Constant Frequency, Burst Mode® Operation and PWM
■ Available in 32-Pin 5mm × 5mm QFN and 28-Pin SSOP Packages

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