DESCRIPTION
The LTC®3709 is a single output, dual phase, synchronous step-down switching regulator. The controller uses a constant on-time, valley current control architecture to deliver very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in input supply voltage. An internal phase-locked loop allows the LTC3709 to be synchronized to an external clock.

FEATURES
■ PolyPhaseTM Valley Current Mode Controller
■ Synchronizable to an External Clock with PLL
■ Coincident or Ratiometric Tracking
■ Sense Resistor Optional
■ 2% to 90% Duty Cycle at 200kHz
■ tON(MIN) < 100ns
■ True Remote Sensing Differential Amplifier
■ High Efficiency at Both Light and Heavy Loads
■ Power Good Output Voltage Monitor
■ 0.6V ±1% Reference
■ Adjustable Current Limit
■ Programmable Soft-Start and Operating Frequency
■ Output Overvoltage Protection
■ Optional Short-Circuit Shutdown Timer
■ 32-Lead (5mm × 5mm) QFN Package

APPLICATIONS
■ Notebook Computers
■ Power Supply for DSP, ASIC, Graphic Processors