Power Management Switching Regulator Step-Down (Buck) Regulators Poly-Phase Buck Controllers
Power Management Switching Regulator Step-Down (Buck) Regulators External Power Switch Buck Controllers

LTC3731 - 3-Phase, 600kHz, Synchronous Buck Switching Regulator Controller

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 Application

LTC3731 Typical Application

Description

The LTC3731 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 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. The precision reference supports output voltages from 0.6V to 6V.

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.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

QFN-32, SSOP-36

LTC3731 Package Drawing
LTC3731 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC3731CG SSOP 36 C $6.16 $4.35 View
LTC3731CG#PBF SSOP 36 C $6.16 $4.35 View
LTC3731CG#TR SSOP 36 C $4.45 View
LTC3731CG#TRPBF SSOP 36 C $4.45 View
LTC3731CUH QFN 32 C $6.52 $4.55 View
LTC3731CUH#PBF QFN 32 C $6.52 $4.55 View
LTC3731CUH#TR QFN 32 C $4.65 View
LTC3731CUH#TRPBF QFN 32 C $4.65 View
LTC3731HG SSOP 36 H $5.92 $5.00 View
LTC3731HG#PBF SSOP 36 H $5.92 $5.00 View
LTC3731HG#TR SSOP 36 H $5.10 View
LTC3731HG#TRPBF SSOP 36 H $5.10 View
LTC3731HUH#PBF QFN 32 H $7.14 $5.00 View
LTC3731HUH#TRPBF QFN 32 H $5.06 View
LTC3731IG SSOP 36 I $6.88 $4.80 View
LTC3731IG#PBF SSOP 36 I $6.88 $4.80 View
LTC3731IG#TR SSOP 36 I $4.90 View
LTC3731IG#TRPBF SSOP 36 I $4.90 View
LTC3731IUH QFN 32 I $5.89 $4.95 View
LTC3731IUH#PBF QFN 32 I $5.89 $4.95 View
LTC3731IUH#TR QFN 32 I $5.05 View
LTC3731IUH#TRPBF QFN 32 I $5.05 View
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology demo boards are offered free of charge to qualified customers. Contact your local sales office or distributor to request a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC438A LTC3731CG | 3-Phase High Efficiency 60A Power Supply, Vin = 9V-14V, Vout = 2.5V/1.8V @ 60A $150.00
DC558A LTC3731CUH | 3-Phase High Efficiency DC/DC Converter, Vin = 5V to 14V, Vout = 1.5V/60A Contact Factory
DC561A-A LTC3731CUH | 12-Phase, 180A High Efficiency Power Supply, 10V - 14Vin, 1.5Vout @ 180A $175.00
DC561A-B LTC3731CUH | 6-Phase, 90A High Efficiency Power Supply, 10V - 14Vin, 1.5Vout @ 90A Contact Factory
DC721A-A LTC3738CUHF LTC3731CUH | 6-Phase, 120A High Efficiency Power Supply, 8 to 14Vin, VRM9.X / 10.X @ 120A Contact Factory
DC721A-B LTC3738CUHF LTC3731CUH | 3-Phase, 65A High Efficiency Power Supply, 8 to 14Vin, VRM9.X / 10.X @ 65A $190.00
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Applications

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

Simulate

LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice IV
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice IV does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As". After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Related models available in LTspice IV
LTC3731
LTC3731H

Technical Support