LINEAR TECHNOLOGY LTC3731 User's Manual
Summary
The LTC3731 is a powerful, high-efficiency synchronous three-phase buck switching regulator controller designed for demanding DC/DC power solutions. This resource details critical features such as phase-lockable frequency generation up to 600kHz per phase and advanced protection against overcurrent and undervoltage. It empowers electrical engineers and designers of high-output current systems, including servers and desktop computer infrastructure, requiring precise power delivery and optimal thermal management.
Page 1 Text Content
LTC3731
3-Phase, 600k Hz,
Synchronous Buck Switching
Regulator Controller FEATURES DESCRIPTIO 3-Phase Current Mode Controller with Onboard The LTC®3731 is a Poly Phase® synchronous step-down MOSFET Drivers switching regulator controller that drives all N-channel ex-
±5% Output Current Matching Optimizes Thermal ternal power MOSFET stages in a phase-lockable fixed fre- Performance and Size of Inductors and MOSFETs quency architecture. The 3-phase controller drives its Differential Amplifier Accurately Senses VOUT output stages with 120° phase separation at frequencies of ±1% VREF Accuracy Over Temperature up to 600k Hz per phase to minimize the RMS current losses Reduced Power Supply Induced Noise in both the input and output filter capacitors. The 3-phase ±10% Power Good Output Indicator technique effectively triples the fundamental frequency, 250k Hz to 600k Hz Per Phase, PLL, Fixed Frequency improving transient response while operating each control- ler at an optimal frequency for efficiency and ease of ther-
PWM, Stage Shedding TM or Burst Mode® Operation
mal design. Light load efficiency is optimized by using a
OPTI-LOOP® Compensation Minimizes COUT
choice of output Stage Shedding or Burst Mode operation.
Adjustable Soft-Start Current Ramping Short-Circuit Shutdown Timer with Defeat Option A differential amplifier provides true remote sensing of both Overvoltage Soft Latch the high and low side of the output voltage at the point of Adjustable Undervoltage Lockout Threshold load. The precision reference supports output voltages from Selectable Phase Output for Up to 12-Phase Operation 0.6V to 6V. Available in 5mm × 5mm QFN and 36-Pin Narrow
Soft-start and a defeatable, timed short-circuit shutdown
(0.209") SSOP Packages
protect the MOSFETs and the load. Current foldback provides protection for the external MOSFETs under
APPLICATIO
short-circuit or overload conditions.
Desktop Computers and Servers , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode,
OPTI-LOOP and Poly Phase are registered trademarks of Linear Technology Corporation.
High Performance Notebook Computers
Stage Shedding is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178,
High Output Current DC/DC Power Supplies
TYPICAL APPLICATIO
VCC 5V TO 28V
TG1VCC
4.5V TO 7V 0.003Ω0.8µH
LTC3731 22µF
10µF SW1
BOOST1
BOOST2 BOOST3
0.1µF SENSE1+ SENSE1–
SW3 SW2 SW1 VIN
POWER GOOD INDICATOR PGOOD 0.003Ω0.8µH VOUT
OPTIONAL SYNC IN PLLIN SW2 1.35V
PLLFLTR BG2 36k PGND
VIN UVADJ
SENSE2+
680p F SENSE2–
ITH TG3
5k RUN/SS
0.01µF SGND BG3 EAIN 100p F
DIFFOUT SENSE3+
SENSE3–IN– COUT
IN+ 470µF
Figure 1. High Current Triple Phase Step-Down Converter
3731fb
Page Summary Contents For LINEAR TECHNOLOGY LTC3731 User's Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 32 |
| File Size | 373.10 KB |
| Published | June 01, 2026 |
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Frequently Asked Questions
What phase separation does the LTC3731 offer?
It offers 120° phase separation at frequencies up to 600kHz per phase.
How can I enhance the transient response and efficiency for this regulator?
Use the Reduced Power Supply Induced Noise technique, which triples the fundamental frequency, or use adjustable Soft-Start/Burst Mode operation.
What protection features are available on the controller?
It includes Short-Circuit Shutdown Timer with defeat option, Overvoltage Soft Latch, and Adjustable Undervoltage Lockout Thresholds.
Does this regulator support multiple output phases?
Yes, it supports selectable phase output for up to 12-Phase Operation.