Analog Devices LTC3731

Description

The LTC®3731 is a PolyPhase® synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable fixedb frequency architecture. The 3-phase controller drives its output stages with 120° phase separation at frequencies of 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.A differential amplifier provides true remote sensing of both the high and low side of the output voltage at the point of load.Soft-start and a defeatable, timed short-circuit shutdown protect the MOSFETs and the load. Current foldback provides protection for the external MOSFETs under short-circuit or overload conditions.

Features

• 3-Phase Current Mode Controller with Onboard MOSFET Drivers
• ±5% Output Current Matching Optimizes Thermal Performance and Size of Inductors and MOSFETs
• Differential Amplifier Accurately Senses VOUT
• ±1% VREF Accuracy Over Temperature
• VOUT Range: 0.6V to 5.5V without Diffamp
• VOUT Range: 0.6V to (VCC – 1.2V) with Diffamp
• 250kHz to 600kHz Per Phase, PLL, Fixed Frequency
• PWM, Stage Shedding™ 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 5mm × 5mm QFN and 36-Pin Narrow (0.209") SSOP Packages

Typical applications

• High Output Current DC/DC Power Supplies
• Servers
• High Performance Notebook Computers
• Desktop Computers

More information

• Datasheet
• IC product information