Features

• 3-Phase Current Mode Controller with Onboard MOSFET Drivers
• ±5% Output Current Matching Optimizes Thermal Performance and Size of Inductors and MOSFETs
• ±2% V_REF Accuracy Over Temperature Up to 140°C
• Reduced Power Supply Induced Noise
• ±10% Power Good Output Indicator
• 225kHz to 680kHz Per Phase, PLL, Fixed Frequency
• PWM, Stage Shedding™ or Burst Mode® Operation
• OPTI-LOOP® Compensation Minimizes C_OUT
• 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 and 5mm × 5mm QFN Packages

Typical Application

Description

The LTC3731H 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 680kHz 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.

The precision reference supports output voltages from 0.6V to 6V. Current foldback provides protection for the external MOSFETs under short-circuit or overload conditions. Please refer to the LTC3731 data sheet for 0°C to 70°C and –40°C to 85°C rated versions.