DESCRIPTION
The LTC®1709-85 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives two 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 an optimum frequency for efficiency. Thermal design is also simplified.

FEATURES
■ Output Stages Operate Antiphase Reducing Input Capacitance Requirements and Power Supply Induced Noise
■ Dual Input Supply Capability for Load Sharing
■ 5-Bit VID Code (VRM 8.5): VOUT = 1.05V to 1.825V
■ True Remote Sensing Differential Amplifier
■ Power Good Output Indicator
■ ±1% Output Voltage Accuracy
■ Active Voltage Positioning Capable
■ Current Mode Control Ensures Current Sharing
■ OPTI-LOOP® Compensation Minimizes COUT
■ Three Operational Modes: PWM, Burst and Cycle Skip
■ Programmable Fixed Frequency: 150kHz to 300kHz
■ Wide VIN Range: 4V to 36V Operation
■ Adjustable Soft-Start Current Ramping
■ Internal Current Foldback and Short-Circuit Shutdown
■ Overvoltage Soft Latch Eliminates Nuisance Trips
■ Available in 36-Lead Narrow SSOP Package

APPLICATIONS
■ Server/Desktop Computers
■ Internet Servers
■ Large Memory Arrays
■ DC Power Distribution Systems