DESCRIPTION
The LTC®1709 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a fixed frequency architecture. The 2-phase controller drives its two output stages out of phase at frequencies up to 300kHz to minimize the RMS ripple currents in both input and output capacitors. The 2-phase technique effectively multiplies the fundamental frequency by two, improving transient response while operating each channel at a optimum frequency for efficiency. Thermal design is also simplified.

FEATURES
■ Two Ouput Stages Operate Antiphase Reducing Input Capacitance and Power Supply Noise
■ 5-Bit VID Control (VRM 8.4 Compliant) VOUT: 1.3V to 3.5V in 50mV/100mV Steps
■ Current Mode Control Ensures Current Sharing
■ True Remote Sensing Differential Amplifier
■ OPTI-LOOPTM Compensation Minimizes COUT
■ Programmable Fixed Frequency: 150kHz to 300kHz—Effective 300kHz to 600kHz Switching Frequency
■ ±1% Output Voltage Accuracy
■ Wide VIN Range: 4V to 36V Operation
■ Adjustable Soft-Start Current Ramping
■ Internal Current Foldback
■ Short-Circuit Shutdown Timer with Defeat Option
■ Overvoltage Soft-Latch Eliminates Nuisance Trips
■ Low Shutdown Current: 20µA
■ Small 36-Lead Narrow (0.209") SSOP Package

APPLICATIONS
■ Desktop Computers
■ Internet/Network Servers
■ Large Memory Arrays
■ DC Power Distribution Systems
■ Battery Chargers