DESCRIPTION
The LTC®1709-8/LTC1709-9 are 2-phase, VID programmable, synchronous step-down switching regulator controllers that drive 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 from 150kHz 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
■ Single Controller Operates Two Output Stages Antiphase Reducing Required Input Capacitance and Power Supply Induced Noise
■ Two 5-Bit Desktop VID Codes:
    LTC1709-8 For VRM8.4 (VOUT from 1.3V to 3.5V)
    LTC1709-9 For VRM9.0 (VOUT from 1.1V to 1.85V)
■ Current Mode Control Ensures Best Current Sharing
■ True Remote Sensing Differential Amplifier
■ Power Good Output Indicator
■ OPTI-LOOPTM Compensation Minimizes COUT
■ Programmable Fixed Frequency: 150kHz to 300kHz
■ ±1% Output Voltage Accuracy
■ 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
■ Low Shutdown Current: 20µA
■ Available in 36-Lead Narrow SSOP Package

APPLICATIONS
■ Workstations
■ Internet Servers
■ Large Memory Arrays
■ DC Power Distribution Systems