DESCRIPTION
The LTC®3737 is a 2-phase dual step-down switching regulator controller that requires few external components. The constant frequency current mode architecture provides excellent AC and DC load and line regulation. MOSFET VDS sensing eliminates the need for current sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are minimized by operating the two controllers out of phase.

FEATURES
■ Sense Resistor Optional
■ Out-of-Phase Controllers Reduce Required
   Input Capacitance
■ Programmable Output Voltage Tracking
■ Constant Frequency Current Mode Architecture
■ Wide VIN Range: 2.75V to 9.8V
■ Wide VOUT Range: 0.6V to VIN
■ 0.6V ±1.5% Reference
■ Low Dropout Operation: 100% Duty Cycle
■ True PLL for Frequency Locking or Adjustment
   (Frequency Range 250kHz to 850kHz)
■ Selectable Burst Mode® or Pulse Skipping Operation
   at Light Loads
■ Internal Soft-Start Circuitry
■ Selectable Maximum Peak Current Sense Threshold
■ Power Good Output Voltage Monitor
■ Output Overvoltage Protection
■ Micropower Shutdown: IQ = 9µA
■ Tiny 4mm × 4mm QFN and 24-Lead SSOP Packages

APPLICATIONS
■ One or Two Lithium-Ion Powered Devices
■ Notebook and Palmtop Computers, PDAs
■ Portable Instruments
■ Distributed DC Power Systems