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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > DC DC Switching Controllers

Analog Devices Inc. LTC3731IUH#TRPBF

Name: LTC3731IUH#TRPBF
Brand: Analog Devices Inc.
SKU: LTC3731IUH#TRPBF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LTC3731IUH#TRPBF

Manufacturer:: Analog Devices Inc.

Category:: DC DC Switching Controllers

Package:: 32-WFQFN Exposed Pad

Datasheet:: LTC3731IUH#TRPBF.pdf

Description:: IC REG CTRLR BUCK 32QFN

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Product details

Overview

LTC3731IUH#TRPBF from Analog Devices (formerly Linear Technology) is a 3-phase, synchronous buck switching regulator controller driving external N-channel MOSFETs in fixed-frequency current-mode operation. It delivers up to 55A output at 1.35V with ±5% phase current matching, 0.6V–5.5V adjustable output voltage, and 250kHz–600kHz per-phase switching frequency-optimized for high-current DC/DC power supplies in servers and high-performance notebooks.

For engineers reviewing the LTC3731IUH#TRPBF datasheet, LTC3731IUH#TRPBF pinout, LTC3731IUH#TRPBF application, or LTC3731IUH#TRPBF equivalent, key selection criteria include its 32-pin 5mm × 5mm QFN package with exposed SGND pad, differential remote sensing capability, PLL-based synchronization support, and configurable light-load modes (Burst Mode® or Stage Shedding™).

Technical Context

The LTC3731IUH#TRPBF implements a constant-frequency, current-mode control architecture with three independent PWM channels operating at 120° phase separation. Each channel features dedicated high- and low-side gate drivers (TGn/BGn), integrated current-sense comparators with matched thresholds (±5% max error), and a transconductance error amplifier (gm = 4–6 mmho) with OPTI-LOOP® compensation.

It integrates a precision differential amplifier (AV = 0.995–1.005 V/V, CMRR ≥ 50 dB) for true remote sensing across load terminals, a phase-locked loop (PLLIN input, PLLFLTR control) enabling synchronization from 250kHz to 600kHz, and dual protection logic: timed short-circuit shutdown via RUN/SS capacitor discharge and overvoltage soft latch via PGOOD monitoring with 100µs fault delay.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Phases	3-phase interleaved operation with 120° phase shift-reduces input/output RMS current by √3, improving capacitor lifetime and thermal design.
Switching Frequency Range	250kHz to 600kHz per phase-adjustable via PLLFLTR voltage (0–2.4V) or external PLLIN sync signal.
Reference Voltage Accuracy	±1% over –40°C to +85°C-ensures stable output regulation under industrial temperature conditions.
Current Sense Threshold	60–90 mV (LTC3731I grade)-sets peak inductor current limit; matched within ±5% across all three phases.
Differential Sensing Range	VOUT = 0.6V to (VCC – 1.2V)-supports accurate remote sensing even at low output voltages with high-side dropout margin.
Gate Driver Capability	TGn/BGn drive strength: 5A peak, tR/tF ≤ 90ns (CLOAD = 3300pF)-enables fast switching of high-Qg MOSFETs with minimal dead-time loss.
Operating Temperature	–40°C to +85°C (I-grade)-qualified for industrial and computing environments requiring extended thermal reliability.

Pinout & Package

Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND). Requires soldering of exposed pad to PCB ground plane for thermal and signal integrity.

Pin/Terminal	Circuit Role	Design Meaning
SW1–SW3	Switch node connections	Interface directly to inductor taps; voltage swing from near-ground to VIN-must be routed with low-inductance paths.
TG1–TG3	Top N-channel gate drivers	Floating outputs referenced to SWn; require bootstrap capacitors and Schottky diodes for high-side drive.
BG1–BG3	Bottom N-channel gate drivers	Ground-referenced outputs; drive MOSFET sources tied to PGND for synchronous rectification.
SENSE1±–SENSE3±	Per-phase current sense inputs	Differential inputs to current comparators; match RSENSE values across phases for balanced current sharing.
IN+, IN–	Differential output voltage sense inputs	Connect directly to load terminals for true remote sensing-eliminates IR drop errors in high-current VRMs.
DIFFOUT	Differential amplifier output	Drives EAIN feedback node; enables precise regulation despite PCB trace resistance between IC and load.
ITH	Error amplifier output / compensation node	Common control voltage for all three current comparators; sets peak inductor current and enables OPTI-LOOP® stability tuning.
RUN/SS	Soft-start timer & short-circuit detection	Capacitor-connected pin controls ramp time to full load and triggers timed shutdown if VOUT drops below 70% nominal.
PGOOD / PHASMD	Combined power-good indicator & phase mode select	In UH package only: open-drain status output (PGOOD) and CLKOUT phase offset selector (30°/60°) share one pin.
VCC	Main supply input	4.5V–7V input powering control circuitry and gate drivers; requires local 0.1µF ceramic decoupling to PGND.
PGND	Power ground	Direct connection point for bottom MOSFET sources and CIN (–) terminal-must be star-connected to minimize noise coupling.
SGND	Signal ground	Separate analog ground reference; routed under IC to PGND then to main ground plane-critical for sensing accuracy.

Key Features

Feature	Design Value
3-phase interleaving with ±5% current matching	Reduces input/output ripple current by √3, allowing smaller input/output capacitors and lower thermal stress on MOSFETs and inductors.
Differential remote sensing (IN+/IN–)	Compensates for PCB trace resistance up to several milliohms-enables <±1% output regulation at point-of-load in VRM applications.
Configurable light-load operation (Burst Mode®/Stage Shedding™)	Extends efficiency down to <1% load: Burst Mode minimizes switching loss; Stage Shedding maintains fixed frequency while disabling unused phases.
OPTI-LOOP® compensation	Minimizes required output capacitance (COUT) by optimizing phase margin without external type-II/type-III networks-simplifies layout and BOM.
PLL synchronization & CLKOUT output	Enables seamless expansion to 6- or 12-phase systems via PHASMD-selectable CLKOUT edge alignment-supports scalable multi-rail power delivery.
Integrated protection suite	Includes timed short-circuit shutdown (via RUN/SS), overvoltage soft latch (PGOOD), undervoltage lockout (UVADJ), and current foldback-reduces need for external fault management circuitry.

Applications

Server VRM Power Delivery	High-Performance Notebook CPU Core Supply
Use Scenario: Delivering 1.35V/55A to dual-socket Xeon processors with tight transient response and thermal constraints. IC Role / Device Role / Timing Role: 3-phase synchronous buck controller managing parallel MOSFET stages with 120° interleaving and differential remote sensing at CPU socket. Use Value: Achieves >90% efficiency at full load while reducing input capacitor RMS current by 90%, lowering heat generation and board area vs single-phase designs.	Use Scenario: Providing dynamically scaled core voltage (0.6V–1.5V) to mobile Intel Core i7/i9 CPUs under burst workloads. IC Role / Device Role / Timing Role: Adaptive 3-phase controller using Stage Shedding™ to maintain fixed-frequency operation down to 1% load while minimizing audible noise. Use Value: Enables seamless transition between active and idle states without frequency dithering-preserves EMI compliance and battery runtime.
High-Density Telecom DC/DC Module	Industrial FPGA/ASIC Core Supply
Use Scenario: Generating 1.2V/40A from 48V intermediate bus in space-constrained telecom line cards. IC Role / Device Role / Timing Role: Interleaved buck controller synchronized via PLLIN to system clock, driving GaN FETs with 600kHz per-phase switching. Use Value: Reduces magnetic component size by tripling effective switching frequency-enables compact, high-power-density module design.	Use Scenario: Powering Xilinx Versal or Intel Agilex FPGA core rails requiring <±1% regulation under rapid load steps (0→30A in 1µs). IC Role / Device Role / Timing Role: Precision 3-phase controller with differential sensing and OPTI-LOOP® compensation delivering fast transient response with minimal output deviation. Use Value: Limits output voltage droop to <30mV during 30A step-prevents FPGA configuration errors and ensures deterministic timing closure.

Server VRM Power Delivery

High-Performance Notebook CPU Core Supply

Use Scenario: Delivering 1.35V/55A to dual-socket Xeon processors with tight transient response and thermal constraints.

IC Role / Device Role / Timing Role: 3-phase synchronous buck controller managing parallel MOSFET stages with 120° interleaving and differential remote sensing at CPU socket.

Use Value: Achieves >90% efficiency at full load while reducing input capacitor RMS current by 90%, lowering heat generation and board area vs single-phase designs.

Use Scenario: Providing dynamically scaled core voltage (0.6V–1.5V) to mobile Intel Core i7/i9 CPUs under burst workloads.

IC Role / Device Role / Timing Role: Adaptive 3-phase controller using Stage Shedding™ to maintain fixed-frequency operation down to 1% load while minimizing audible noise.

Use Value: Enables seamless transition between active and idle states without frequency dithering-preserves EMI compliance and battery runtime.

High-Density Telecom DC/DC Module

Industrial FPGA/ASIC Core Supply

Use Scenario: Generating 1.2V/40A from 48V intermediate bus in space-constrained telecom line cards.

IC Role / Device Role / Timing Role: Interleaved buck controller synchronized via PLLIN to system clock, driving GaN FETs with 600kHz per-phase switching.

Use Value: Reduces magnetic component size by tripling effective switching frequency-enables compact, high-power-density module design.

Use Scenario: Powering Xilinx Versal or Intel Agilex FPGA core rails requiring <±1% regulation under rapid load steps (0→30A in 1µs).

IC Role / Device Role / Timing Role: Precision 3-phase controller with differential sensing and OPTI-LOOP® compensation delivering fast transient response with minimal output deviation.

Use Value: Limits output voltage droop to <30mV during 30A step-prevents FPGA configuration errors and ensures deterministic timing closure.

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-phase synchronous buck controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MP2940AGQ-Z	4-phase controller with integrated MOSFET drivers; supports up to 700kHz; no differential sensing; uses internal VREF (0.6V ±1.5%).	Targeted at cost-sensitive consumer SSDs and GPUs-not rated for industrial temp range or high-precision remote sensing.	Select MP2940AGQ-Z only when phase count >3 is needed and differential sensing is unnecessary; verify thermal derating for 55A operation.
ISL95831IRZ-T	3-phase controller with integrated telemetry ADC; supports SVID interface; 0.5V–1.5V VREF range; no PLL sync or Stage Shedding™.	Designed specifically for Intel VR13/VR14 CPU power delivery with SMBus control-not suitable for standalone FPGA or telecom applications.	Choose ISL95831IRZ-T only for Intel-compatible platforms requiring SVID communication; LTC3731IUH#TRPBF offers broader flexibility in non-SVID systems.

Compared with MP2940AGQ-Z and ISL95831IRZ-T, the LTC3731IUH#TRPBF uniquely combines differential remote sensing, PLL-based synchronization, and dual light-load modes-making it optimal for high-accuracy, thermally constrained, and scalable multi-phase power designs outside standardized CPU VRMs.

Availability

LTC3731IUH#TRPBF is available at Aetrix Electronics and suitable for server VRM development, high-performance notebook power design, and industrial FPGA/ASIC core supply applications requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for LTC3731IUH#TRPBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LTC portfolio.

The LTC3731IUH#TRPBF belongs to Linear's high-performance PolyPhase® controller family, designed specifically for high-current, low-voltage DC/DC conversion in computing, telecom, and industrial systems where efficiency, thermal management, and precision regulation are critical.

FAQ

What is the maximum output current supported by the LTC3731IUH#TRPBF in a typical 3-phase design?

The LTC3731IUH#TRPBF itself does not set absolute current limits-it controls external N-channel MOSFETs. In the standard evaluation circuit (Figure 1), it delivers 55A at 1.35V using 3×0.8µH inductors and 3×0.003Ω sense resistors. Actual current capability depends on MOSFET RDS(on), thermal design, and PCB copper weight. The controller's current sense threshold is 60–90mV with ±5% matching across phases, enabling balanced current sharing up to ~60A with proper layout and cooling for the LTC3731IUH#TRPBF.

Does the LTC3731IUH#TRPBF support synchronization to an external clock source?

Yes, the LTC3731IUH#TRPBF supports full PLL-based synchronization via the PLLIN pin. When an external clock signal is applied to PLLIN, the internal phase detector locks the rising edge of TG1 to that signal's rising edge. The PLLFLTR pin serves both as the PLL filter node and a DC voltage input (0–2.4V) to set free-running frequency from 250kHz to 600kHz. This allows precise coordination across multiple LTC3731IUH#TRPBF controllers or with other PolyPhase® devices in multi-rail systems.

How does the differential sensing feature of the LTC3731IUH#TRPBF improve regulation accuracy?

The LTC3731IUH#TRPBF's differential amplifier accepts IN+ and IN– inputs directly at the load terminals, rejecting common-mode voltage drop across PCB traces and interconnects. With 0.995–1.005 V/V gain, <5mV offset, and ≥50dB CMRR, it maintains <±1% output regulation even with 10–20mΩ total path resistance-critical for VRM applications where 10mV error at 1.2V equals 0.83% deviation. This eliminates reliance on single-point feedback and prevents ground-loop-induced instability in the LTC3731IUH#TRPBF control loop.

What are the key differences between Burst Mode® and Stage Shedding™ operation in the LTC3731IUH#TRPBF?

Burst Mode® (FCB < 0.6V) disables switching cycles entirely during light load, reducing quiescent current and maximizing efficiency below ~5% load-but introduces variable-frequency operation and potential EMI spread. Stage Shedding™ (FCB = VCC) maintains fixed frequency while sequentially disabling phases: at ~10% load, two phases shut down; below 1% load, only Phase 1 operates discontinuously. This preserves EMI predictability and avoids acoustic noise-making Stage Shedding™ preferable for noise-sensitive applications using the LTC3731IUH#TRPBF.

Can the LTC3731IUH#TRPBF be used in a single-phase configuration?

Yes, the LTC3731IUH#TRPBF can operate in single-phase mode by connecting only one set of TG/BG/SW/SENSE pins and leaving others unconnected or grounded per datasheet guidelines. However, doing so forfeits interleaving benefits (lower ripple, better thermal distribution) and wastes two-thirds of the controller's capability. For true single-phase needs, Analog Devices recommends lower-cost alternatives like the LTC3774 or LTC3855. The LTC3731IUH#TRPBF is optimized for 3-phase use-its value lies in current matching, phase synchronization, and shared ITH compensation across all channels.

LTC3731IUH#TRPBF Specifications

Product attributes: Attribute value

Manufacturer:: Analog Devices Inc.

Series:: PolyPhase®

Package/Case:: 32-WFQFN Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Type:: Transistor Driver

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Number of Outputs:: 3

Output Phases:: 3

Voltage - Supply (Vcc/Vdd):: 3.8V ~ 7V

Frequency - Switching:: 225kHz ~ 680kHz

Duty Cycle (Max):: 98.5%

Synchronous Rectifier:: Yes

Clock Sync:: No

Serial Interfaces:: -

Control Features:: Enable, Phase Control, Power Good, Soft Start

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 32-QFN (5x5)

LTC3731IUH#TRPBF FAQ

1.How can I place an order for LTC3731IUH#TRPBF through Aetrix?

Please submit a Request for Quotation (RFQ) for LTC3731IUH#TRPBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LTC3731IUH#TRPBF reliable?

The price and inventory of LTC3731IUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3731IUH#TRPBF is usually 5 days.

3.What payment methods are accepted for LTC3731IUH#TRPBF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3731IUH#TRPBF transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LTC3731IUH#TRPBF?

LTC3731IUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LTC3731IUH#TRPBF order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LTC3731IUH#TRPBF?

For technical support, including LTC3731IUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3731IUH#TRPBF requirements.

6.How does Aetrix verify that LTC3731IUH#TRPBF is sourced from the original manufacturer or authorized distributors?

All LTC3731IUH#TRPBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC3731IUH#TRPBF meets industry standards.

7.What is the process for return or replacement of LTC3731IUH#TRPBF?

All LTC3731IUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3731IUH#TRPBF, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LTC3731IUH#TRPBF part is unused and in its original packaging.

Return procedure for LTC3731IUH#TRPBF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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