Features

• PolyPhase^TM 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
• t_ON(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

Typical Application

Description

The LTC3709 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.

A TRACK pin is provided for tracking or sequencing the output voltage among several LTC3709 chips or an LTC3709 and other DC/DC regulators. Soft-start is accomplished using an external timing capacitor.

Fault protection is provided by an output overvoltage comparator and an optional short-circuit shutdown timer. The current limit level is user programmable. A wide supply range allows voltages as high as 31V to step down to 0.6V.

Protected by U.S. Patents, including 5481178, 6476589, 6144194, 5847554, 6177678, 6304066, 6580258, 6674274, 6462525, 6593724.