DESCRIPTION
The LTC® 3731H is a PolyPhase® synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable fixed frequency architecture. The LTC3731H is rated for operation up to 140°C junction temperature. The 3-phase controller drives its output stages with 120°phase separation at frequencies up to 600kHz per phase to minimize the RMS current losses in both the input and output filter capacitors. The 3-phase technique effectively triples the fundamental frequency, improving transient response while operating each controller at an optimal frequency for efficiency and ease of thermal design. Light load efficiency is optimized by using a choice of output Stage Shedding or Burst Mode operation.

FEATURES
■ 3-Phase Current Mode Controller with Onboard MOSFET Drivers
■ ±5% Output Current Matching Optimizes Thermal Performance and Size of Inductors and MOSFETs
■ ±2% VREFAccuracy Over Temperature up to 140°C
■ Reduced Power Supply Induced Noise
■ ±10% Power Good Output Indicator
■ 250kHz to 600kHz Per Phase, PLL, Fixed Frequency
■ PWM, Stage SheddingTM or Burst Mode® Operation
■ OPTI-LOOP® Compensation Minimizes COUT
■ Adjustable Soft-Start Current Ramping
■ Short-Circuit Shutdown Timer with Defeat Option
■ Overvoltage Soft Latch
■ Adjustable Undervoltage Lockout Threshold
■ Selectable Phase Output for Up to 12-Phase Operation
■ Available in 36-Pin Narrow (0.209") SSOP Package

APPLICATIONS
■ Automotive and Industrial Power Supplies
■ High Output Current DC/DC Power Supplies