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Analog Devices Inc. LTC3731CUH#TRPBF
- Part No.:
- LTC3731CUH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3731CUH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,743
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Product details
Overview
LTC3731CUH#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 architecture. It operates up to 600kHz per phase with 120° phase separation, delivers ±5% output current matching across phases, supports 0.6V–5.5V output voltage range, and integrates differential remote sensing for precision load-point regulation - deployed in high-current server VRMs and notebook CPU power stages.
For engineers reviewing the LTC3731CUH#TRPBF datasheet, LTC3731CUH#TRPBF pinout, LTC3731CUH#TRPBF application, or LTC3731CUH#TRPBF equivalent, key selection criteria include phase-lockable 250–600kHz operation, Stage Shedding™/Burst Mode® light-load optimization, OPTI-LOOP® compensation, ±1% VREF accuracy over temperature, and true differential VOUT sensing capability.
Technical Context
The LTC3731CUH#TRPBF implements a constant-frequency, current-mode control loop with three independent PWM channels, each featuring dedicated SENSE+ and SENSE− inputs, ITH-based current threshold scaling, and synchronized top/bottom gate drivers (TGn/BGn) with <90ns rise/fall times. Its PLL architecture accepts external synchronization via PLLIN and allows frequency tuning from 250kHz to 600kHz using the PLLFLTR pin voltage.
It integrates a unity-gain differential amplifier (IN+/IN− → DIFFOUT) with 0.995–1.005 gain, <5mV input offset, and 50–70dB CMRR for remote sensing, plus a transconductance error amplifier (gm = 4–7 mmho) with 3MHz GBW. The device supports forced continuous, Burst Mode®, and Stage Shedding™ operation selected via the FCB pin, and includes short-circuit shutdown with timed latch-off and overvoltage soft-latch protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 3-phase synchronous buck controller with external N-MOSFETs |
| Switching Frequency | 250–600kHz per phase, adjustable via PLLFLTR voltage or external sync |
| Output Voltage Range | 0.6V to 5.5V without diffamp; 0.6V to (VCC – 1.2V) with diffamp |
| VREF Accuracy | ±1% over 0°C to 70°C ambient (LTC3731C grade) |
| Current Matching | ±5% max mismatch between phases at full load |
| Differential Sensing | True IN+/IN− remote sense with 0.995–1.005 gain and <5mV offset |
| Gate Drive Capability | TGn/BGn drivers support 5A peak, 30–90ns tR/tF into 3300pF |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed SGND pad (pin 33), rated for 0°C to 70°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST1–BOOST3 | Floating top-gate supply | Bootstrapped voltage source for TG1–TG3; swing = VCC to VCC + VIN |
| TG1–TG3 | Top N-MOSFET gate drive | High-side floating driver outputs; voltage swing referenced to SWn |
| BG1–BG3 | Bottom N-MOSFET gate drive | Low-side drivers referenced to PGND; 0V to VCC swing |
| SENSE1±–SENSE3± | Per-phase current sense inputs | Differential inputs to current comparators; set trip threshold with RSENSE and ITH |
| IN+, IN− | Differential remote sense inputs | Connect to load VOUT+ and VOUT−; enable true point-of-load regulation |
| DIFFOUT | Differential amplifier output | Drives EAIN to close feedback loop; supports 10mA sourcing |
| ITH | Error amplifier output / compensation node | Controls all three current comparator thresholds; connects to RC network for OPTI-LOOP® |
| FCB | Operating mode select | Logic-controlled input: GND = forced continuous, open = Burst Mode®, VCC = Stage Shedding™ |
| PHASMD/PG | Phase shift / PGOOD dual-function | In UH package only: sets CLKOUT phase offset (30°/60°); also serves as open-drain PGOOD output |
| RUN/SS | Soft-start & short-circuit timer | Capacitor sets ramp time and latched shutdown delay; discharges under severe overload |
Key Features
| Feature | Design Value |
|---|---|
| 3-Phase PolyPhase® Architecture | 120° phase interleaving reduces input/output RMS current by ~58%, enabling smaller capacitors and lower thermal stress |
| Stage Shedding™ Operation | Disables two phases below ~10% load, eliminating gate charge and switching losses while maintaining fixed-frequency operation |
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing loop stability with minimal COUT ESR dependency |
| Differential Remote Sensing | IN+/IN− inputs reject PCB trace IR drop and ground noise, ensuring ±0.5% regulation accuracy at load point |
| Programmable Undervoltage Lockout | UVADJ pin sets precise turn-on threshold (1.13–1.23V) for controlled system power-up sequencing |
| Short-Circuit Protection | Timed RUN/SS discharge provides configurable latch-off after sustained <70% VOUT condition, protecting MOSFETs and load |
Applications
| Server VRM Power Stage | Notebook CPU Core Supply |
|---|---|
Use Scenario: High-current, low-voltage power delivery to multi-core Xeon or EPYC processors in 1U/2U rack servers. IC Role / Device Role / Timing Role: 3-phase synchronous buck controller managing parallel MOSFET banks with phase-interleaved timing to reduce input ripple and thermal hotspots. Use Value: ±5% inter-phase current matching ensures balanced thermal loading across inductors and MOSFETs, extending component lifetime and simplifying thermal design. |
Use Scenario: Dynamic voltage scaling for Intel Core i7/i9 or AMD Ryzen mobile CPUs under burst workloads. IC Role / Device Role / Timing Role: Adaptive 3-phase controller supporting Burst Mode® and Stage Shedding™ to maintain >90% efficiency from 1A to 55A load range. Use Value: Differential sensing compensates for motherboard plane resistance, delivering stable 1.35V ±10mV at CPU socket despite 50mΩ interconnect loss. |
| High-Density DC/DC Module | Industrial FPGA Core Supply |
Use Scenario: Compact 50A, 12V-to-1.2V intermediate bus converter in telecom line cards or AI accelerators. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller with PLL synchronization enabling seamless stacking of multiple LTC3731 units for 6- or 12-phase operation. Use Value: CLKOUT and PHASMD pins allow deterministic phase alignment across controllers, minimizing system-level EMI peaks and easing filter design. |
Use Scenario: Reliable core rail for Xilinx Versal or Intel Agilex FPGAs requiring tight transient response and ±1% output tolerance. IC Role / Device Role / Timing Role: Precision-regulated 3-phase controller with ±1% VREF and 100µs PGOOD fault reporting for FPGA configuration safety. Use Value: Overvoltage soft-latch and differential sensing prevent FPGA damage during hot-swap events or board-level voltage surges. |
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 |
|---|---|---|---|
| LTC3833EUH#TRPBF | Single-phase controller; no phase interleaving, no PLL sync, no Stage Shedding™; 600kHz max, 0.6–5V VOUT | Suitable only for ≤25A loads; lacks multiphase current balancing and remote sensing | Select when cost-sensitive single-rail designs require simplicity over high-current scalability |
| MP2940AGQ-Z | 3-phase controller with integrated MOSFET drivers but no differential sensing; 400kHz max; ±2% VREF; uses analog current sharing | Lower accuracy remote sensing; no Burst Mode®; requires external current-sharing resistors | Choose for space-constrained industrial supplies where ±2% regulation suffices and layout simplicity outweighs precision |
Compared with LTC3731CUH#TRPBF, LTC3833EUH#TRPBF offers lower integration cost but sacrifices phase interleaving benefits and load-point accuracy, while MP2940AGQ-Z provides compact 3-phase control without differential sensing or Stage Shedding™, limiting its use in high-precision, high-transient CPU/FPGA rails.
Availability
LTC3731CUH#TRPBF is available at Aetrix Electronics and suitable for server VRMs, notebook CPU power stages, and high-density DC/DC modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3731CUH#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 its high-performance power management portfolio with rigorous automotive-grade reliability and military-qualified process controls.
The LTC3731CUH#TRPBF belongs to Linear's PolyPhase® controller family, engineered specifically for high-efficiency, high-current digital power delivery in computing and datacenter applications demanding precision regulation and thermal scalability.
FAQ
What is the operating temperature range for the LTC3731CUH#TRPBF?
The LTC3731CUH#TRPBF is specified for 0°C to 70°C ambient operation (Commercial grade). Its thermal performance is enhanced by the 5mm × 5mm QFN package with exposed SGND pad, achieving θJA = 34°C/W - significantly lower than the SSOP variant - enabling higher power density in thermally constrained layouts. This rating applies strictly to the CUH suffix part; industrial-grade variants (IUH) extend to –40°C to 85°C.
How does the PHASMD/PG pin function in the LTC3731CUH#TRPBF?
In the LTC3731CUH#TRPBF, the PHASMD/PG pin combines two functions: phase shift selection and power-good indication. When pulled low, it configures CLKOUT to lead TG1 by 30°; when pulled high, the offset becomes 60° - enabling deterministic expansion to 6- or 12-phase systems. Simultaneously, it serves as an open-drain PGOOD output that pulls low if VOUT deviates >±10% for >100µs. This dual-role pin is unique to the UH package and not present in the SSOP version.
Can the LTC3731CUH#TRPBF operate without the differential amplifier?
Yes, the LTC3731CUH#TRPBF can operate without the differential amplifier by bypassing IN+ and IN− and feeding feedback directly to EAIN via a resistor divider from VOUT. In this configuration, the output voltage range expands to 0.6V–5.5V, and regulation relies on local sensing only. However, removing differential sensing forfeits remote load-point accuracy, making the design vulnerable to PCB trace resistance errors - especially critical in high-current (>20A) applications where even 10mΩ drop causes >20mV regulation error.
What protection features does the LTC3731CUH#TRPBF include?
The LTC3731CUH#TRPBF integrates short-circuit shutdown with timed latch-off (via RUN/SS capacitor discharge), overvoltage soft-latch, undervoltage lockout (adjustable via UVADJ), current foldback limiting, and thermal shutdown. Its differential amplifier also enables precise PGOOD monitoring with ±10% window and 100µs fault delay. Unlike basic controllers, it avoids hard latch-off on overvoltage - instead reducing duty cycle gradually - preserving system recoverability during transient spikes.
How is light-load efficiency optimized in the LTC3731CUH#TRPBF?
The LTC3731CUH#TRPBF optimizes light-load efficiency via three selectable modes controlled by the FCB pin: Burst Mode® (FCB floating) minimizes switching losses by gating entire PWM bursts; Stage Shedding™ (FCB = VCC) disables two phases below ~10% load while maintaining fixed frequency; and forced continuous mode (FCB = GND) sustains full 3-phase operation. Each mode trades off ripple, noise, and efficiency - Burst Mode® achieves highest efficiency (<100mW at 1A), while Stage Shedding™ preserves EMI predictability.
LTC3731CUH#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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3731CUH#TRPBF FAQ
1.How can I place an order for LTC3731CUH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3731CUH#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 LTC3731CUH#TRPBF reliable?
The price and inventory of LTC3731CUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3731CUH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3731CUH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3731CUH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3731CUH#TRPBF?
LTC3731CUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3731CUH#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 LTC3731CUH#TRPBF?
For technical support, including LTC3731CUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3731CUH#TRPBF requirements.
6.How does Aetrix verify that LTC3731CUH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3731CUH#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 LTC3731CUH#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3731CUH#TRPBF?
All LTC3731CUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3731CUH#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 LTC3731CUH#TRPBF part is unused and in its original packaging.
Return procedure for LTC3731CUH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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