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Analog Devices Inc. LTC3731IG#TRPBF
- Part No.:
- LTC3731IG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC3731IG#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,253
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Product details
Overview
LTC3731IG#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 VOUT, and 250kHz–600kHz per-phase switching frequency. It is used in high-current DC/DC power supplies for servers and high-performance notebooks.
For engineers reviewing the LTC3731IG#TRPBF datasheet, LTC3731IG#TRPBF pinout, LTC3731IG#TRPBF application, or LTC3731IG#TRPBF equivalent, key selection criteria include its 3-phase PolyPhase® architecture, differential remote sensing capability, OPTI-LOOP® compensation, Stage Shedding™/Burst Mode® light-load optimization, and support for up to 12-phase expansion via CLKOUT and PHASMD.
Technical Context
The LTC3731IG#TRPBF implements a constant-frequency, current-mode control loop with three independent PWM channels operating at 120° phase separation. Each channel uses an internal transconductance error amplifier (gm = 4–7 mmho), ITH-based current threshold modulation, and synchronized top/bottom gate drivers with 30–90 ns rise/fall times.
Its PLL architecture enables synchronization to external clocks via PLLIN or precise frequency tuning via PLLFLTR (0–2.4V sets 190–750 kHz). The integrated differential amplifier (AV = 0.995–1.005 V/V, CMRR = 50–70 dB) supports true remote sensing at the load, while protection features include short-circuit shutdown timer, overvoltage soft latch, and adjustable undervoltage lockout (UVADJ threshold = 1.13–1.23 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VOUT Range | 0.6V to 5.5V without diffamp; 0.6V to (VCC – 1.2V) with diffamp - enables wide-core-voltage regulation including sub-1V CPU/GPU rails. |
| Switching Frequency | 250kHz to 600kHz per phase - balances efficiency, thermal design, and transient response; 3× effective ripple frequency reduces input/output capacitor RMS stress. |
| Current Matching | ±5% max phase current mismatch - ensures balanced thermal loading across inductors and MOSFETs in multi-phase layouts. |
| VREF Accuracy | ±1% over temperature - guarantees tight output voltage regulation under varying ambient and load conditions. |
| Differential Sensing | IN+/IN− inputs with 0.5–5 mV offset and 50–70 dB CMRR - rejects PCB trace IR drop and ground noise for accurate point-of-load regulation. |
| Operating Temp | –40°C to +85°C (I-grade) - qualified for industrial and computing environments with extended thermal margins. |
| Package | 36-pin narrow SSOP (0.209") - surface-mount compatible with standard reflow profiles; exposed pad not present (vs. QFN UH variant). |
Pinout & Package
Package: 36-lead plastic SSOP (G package), 0.209" width, JEDEC MS-013AC. Thermal resistance θJA = 95°C/W, θJC = 32°C/W. Not a QFN - no exposed thermal pad.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main supply input | 4.5V–7V logic and driver supply; requires local 0.1µF decoupling to PGND for stable gate drive. |
| PGND | Power ground return | Direct connection point for bottom MOSFET sources and CIN(–); must be low-inductance path to minimize switching noise. |
| TG1–TG3 | Top gate drivers | Floating N-channel drivers with bootstrapped operation; swing = BOOSTn – SWn (max 7V), rated for 5A peak. |
| BG1–BG3 | Bottom gate drivers | Ground-referenced N-channel drivers; swing = 0V to VCC, rated for 5A peak; VDR pin used only in G-package variants. |
| SENSE1+ to SENSE3– | Per-phase current sense inputs | Differential inputs to current comparators; threshold set by ITH voltage and RSENSE; supports 60–90 mV max sense range. |
| IN+, IN– | Differential output voltage sense | High-precision inputs to internal unity-gain diffamp; enables Kelvin sensing at load to eliminate PCB IR drop error. |
| RUN/SS | Soft-start & fault timer | Capacitor-based ramp controls startup current slew rate and provides timed short-circuit shutdown (defeatable). |
| PLLIN / PLLFLTR | Frequency sync interface | PLLIN accepts external clock for phase locking; PLLFLTR sets oscillator frequency (0–2.4V → 190–750 kHz) or filters PLL loop. |
| PHASMD | CLKOUT phase shift select | Logic-level input selecting 30° (low) or 60° (high) phase offset between TG1 and CLKOUT - enables 6-/12-phase cascading. |
| PGOOD | Power-good indicator | Open-drain output asserting low if VOUT deviates >±10% for ≥100 µs; includes built-in delay and hysteresis. |
Key Features
| Feature | Design Value |
|---|---|
| PolyPhase® 3-phase architecture | 120° interleaved switching reduces input/output capacitor RMS current by ~58%, enabling smaller, cooler, higher-reliability filter designs. |
| OPTI-LOOP® compensation | Minimizes required output capacitance (COUT) by optimizing loop stability across load and line variations without external type-II/type-III networks. |
| Stage Shedding™ and Burst Mode® | Automatically disables phases below ~10% load (shedding) or enters burst cycles below ~1% load - maximizes light-load efficiency without audible noise. |
| Differential remote sensing (IN+/IN–) | Rejects up to 5 mV of common-mode noise and compensates for PCB trace resistance - critical for <1% regulation accuracy in VRM applications. |
| Adjustable UVLO via UVADJ pin | Programmable shutdown threshold (1.13–1.23 V) allows custom input rail sequencing and brown-out protection aligned with system power-up requirements. |
Applications
| Server VRM Power Delivery | High-Performance Notebook CPU Core Supply |
|---|---|
|
Use Scenario: Delivering 55A @ 1.35V to dual-socket Xeon processors with tight transient response and thermal uniformity. IC Role / Device Role / Timing Role: 3-phase synchronous buck controller managing three parallel power stages with 120° phase shift and differential remote sensing. Use Value: ±5% phase current matching minimizes hot-spot formation on PCB and enables smaller, lower-DCR inductors versus single-phase solutions. |
Use Scenario: Regulating GPU core voltage in thin-and-light notebooks where board space and thermal envelope are constrained. IC Role / Device Role / Timing Role: High-efficiency multiphase controller supporting Burst Mode® for idle power savings and fast load-step response during graphics bursts. Use Value: OPTI-LOOP® compensation reduces required output capacitance by up to 40%, saving PCB area and BOM cost without sacrificing stability. |
| High-Output-Current Telecom DC/DC Module | Industrial FPGA/ASIC Core Rail |
|
Use Scenario: Generating 40A @ 0.85V for baseband processing units in 5G radio equipment with strict EMI and thermal limits. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller with PLL synchronization to system clock for deterministic EMI shaping. Use Value: 250–600 kHz per-phase tunability allows EMI peak avoidance while maintaining optimal MOSFET switching loss trade-off. |
Use Scenario: Powering 28nm/16nm FPGA cores requiring <±1% regulation accuracy across –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Precision reference controller with ±1% VREF accuracy and differential sensing to reject board-level noise in dense mixed-signal layouts. Use Value: 0.6V–5.5V VOUT range and –40°C to +85°C rating support next-gen low-voltage, high-current digital loads in harsh environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiphase buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL95812IRZ-T | 4-phase controller with integrated MOSFET drivers; supports up to 1MHz; lacks differential sensing and Stage Shedding™. | Better suited for compact, lower-current (<30A) applications where integration outweighs remote sensing need. | Select ISL95812IRZ-T when board space is critical and differential sensing is unnecessary; verify thermal derating for >40A operation. |
| MP2940AGQSE-Z | 3-phase controller with PMBus interface, telemetry, and digital loop compensation; requires external EEPROM; no Burst Mode®. | Ideal for systems needing real-time telemetry, adaptive loop tuning, or firmware-configurable protection thresholds. | Choose MP2940AGQSE-Z when digital monitoring, programmable fault responses, or dynamic loop adjustment are required. |
Compared with ISL95812IRZ-T and MP2940AGQSE-Z, the LTC3731IG#TRPBF offers superior analog precision (±1% VREF, ±5% current match), native differential sensing, and analog light-load optimization - making it preferred for high-accuracy, high-current analog VRMs where digital overhead is unnecessary.
Availability
LTC3731IG#TRPBF is available at Aetrix Electronics and suitable for server VRM designs, high-performance notebook power delivery, and industrial FPGA/ASIC core supplies requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3731IG#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 all Linear ICs including the LTC3731 series.
The LTC3731IG#TRPBF belongs to Linear's high-performance power controller family, designed specifically for high-current, low-voltage DC/DC conversion in computing and telecom infrastructure where phase interleaving, precision regulation, and thermal efficiency are critical.
FAQ
What is the maximum output current supported by the LTC3731IG#TRPBF?
The LTC3731IG#TRPBF itself does not set a hard current limit - it drives external N-channel MOSFETs. In the typical application (Figure 1), it delivers 55A at 1.35V using three parallel 0.8µH inductors and 0.003Ω sense resistors. Actual current capability depends on MOSFET selection, layout, thermal design, and input voltage range (5V–28V). The controller supports ≥60A with optimized components.
Does the LTC3731IG#TRPBF support differential remote sensing?
Yes, the LTC3731IG#TRPBF includes dedicated IN+ and IN– pins connected to a precision unity-gain differential amplifier (AV = 0.995–1.005, VOS ≤ 5 mV). This enables true Kelvin sensing at the load, rejecting PCB trace resistance errors and improving regulation accuracy to ±1% even with milliohm-level interconnect drops - essential for VRM applications.
How does the LTC3731IG#TRPBF handle light-load efficiency?
The LTC3731IG#TRPBF offers three selectable light-load modes via the FCB pin: Burst Mode® (FCB floating), Stage Shedding™ (FCB = VCC), or forced continuous conduction (FCB = GND). Stage Shedding™ shuts down two phases below ~10% load, reducing gate charge and switching losses; Burst Mode® further disables all phases intermittently below ~1% load for peak efficiency without audible noise.
What package type is used for the LTC3731IG#TRPBF?
The LTC3731IG#TRPBF uses a 36-lead narrow-body plastic SSOP (G package), 0.209" wide, per JEDEC MS-013AC. It is distinct from the 5mm × 5mm QFN (UH package) variant. This SSOP package has no exposed thermal pad and relies on θJA = 95°C/W for thermal dissipation - appropriate for moderate-power, cost-sensitive board-level designs.
Can the LTC3731IG#TRPBF be synchronized to an external clock?
Yes, the LTC3731IG#TRPBF supports full PLL-based synchronization via the PLLIN pin. When an external clock is applied, the internal oscillator locks to its rising edge with minimal jitter. The PLLFLTR pin serves both as the PLL loop filter node and as a DC voltage input (0–2.4V) to manually set frequency from 190kHz to 750kHz - enabling deterministic EMI control and multi-controller coherence.
LTC3731IG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 36-SSOP (0.209", 5.30mm Width)
- 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:
- 36-SSOP
LTC3731IG#TRPBF FAQ
1.How can I place an order for LTC3731IG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3731IG#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 LTC3731IG#TRPBF reliable?
The price and inventory of LTC3731IG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3731IG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3731IG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3731IG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3731IG#TRPBF?
LTC3731IG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3731IG#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 LTC3731IG#TRPBF?
For technical support, including LTC3731IG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3731IG#TRPBF requirements.
6.How does Aetrix verify that LTC3731IG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3731IG#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 LTC3731IG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3731IG#TRPBF?
All LTC3731IG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3731IG#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 LTC3731IG#TRPBF part is unused and in its original packaging.
Return procedure for LTC3731IG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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