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Analog Devices Inc. LTC3731CG#TRPBF
- Part No.:
- LTC3731CG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC3731CG#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,355
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Product details
Overview
LTC3731CG#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 desktop/server applications.
For engineers reviewing the LTC3731CG#TRPBF datasheet, LTC3731CG#TRPBF pinout, LTC3731CG#TRPBF application, or LTC3731CG#TRPBF equivalent, key selection criteria include its PolyPhase® architecture, differential remote sensing capability, Stage Shedding™/Burst Mode® light-load optimization, and support for up to 12-phase expansion via CLKOUT/PLLIN synchronization.
Technical Context
The LTC3731CG#TRPBF implements a constant-frequency, peak-current-mode control loop with three independent PWM channels operating at 120° phase separation. Each channel features dedicated ITH-based current threshold scaling, synchronized top/bottom gate drivers (TGn/BGn), and integrated differential amplifier for true point-of-load sensing.
Its PLL architecture accepts external sync via PLLIN and allows frequency tuning from 250kHz to 600kHz through PLLFLTR voltage (0–2.4V), while OPTI-LOOP® compensation minimizes output capacitance requirements. Protection includes short-circuit shutdown with timed latch-off, overvoltage soft-latch, and adjustable undervoltage lockout via UVADJ.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 3-phase synchronous buck controller with external N-MOSFETs |
| Switching Frequency Range | 250kHz–600kHz per phase; PLL-synchronizable across multiple controllers |
| Output Voltage Range | 0.6V–5.5V without diffamp; 0.6V–(VCC–1.2V) with diffamp for remote sensing |
| Reference Accuracy | ±1% over temperature (0°C to 70°C) - ensures tight VOUT regulation under thermal drift |
| Current Matching | ±5% max phase-to-phase output current mismatch - enables balanced thermal loading and smaller magnetics |
| Operating Temp Range | 0°C to 70°C - specified for commercial-grade server/desktop power systems |
| Differential Sensing Gain | 0.995–1.005 V/V with <5mV offset - supports accurate remote sensing across PCB voltage drops |
Pinout & Package
Package: 36-lead plastic SSOP (G package), 0.209" narrow body, exposed pad not present. Thermal resistance θJA = 95°C/W, θJC = 32°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main supply input | 4.5V–7V bias for internal logic and gate drivers; requires local 0.1µF decoupling to PGND |
| TG1–TG3 | Top gate drivers | Floating high-side outputs driving N-MOSFET gates; swing equals BOOSTn voltage superimposed on SWn |
| BG1–BG3 | Bottom gate drivers | Ground-referenced low-side outputs; swing from 0V to VCC |
| SENSE1+ to SENSE3– | Per-phase current sense inputs | Differential inputs to current comparators; set trip threshold with RSENSE and ITH voltage |
| IN+, IN– | Differential remote sense inputs | High-precision unity-gain inputs for true point-of-load feedback; reject ground noise up to 70dB CMRR |
| ITH | Error amplifier output | Compensation node and master current threshold control; sets all three phase peak currents simultaneously |
| PLLIN / PLLFLTR | Synchronization interface | PLLIN accepts external clock; PLLFLTR sets oscillator frequency or receives phase detector output |
| RUN/SS | Soft-start & fault timer | Capacitor sets ramp time and short-circuit timeout; discharges during overload to trigger shutdown |
| PGOOD | Power-good indicator | Open-drain output asserting after 100µs delay when VOUT stays within ±10% window |
Key Features
| Feature | Design Value |
|---|---|
| PolyPhase® 3-phase architecture | 120° phase interleaving reduces input/output RMS current by √3, cutting capacitor size and ESR losses by ~67% |
| Stage Shedding™ mode | Disables two phases below ~10% load, eliminating gate charge and switching losses while maintaining fixed-frequency operation |
| Differential remote sensing | IN+/IN− inputs with 0.5mV typical offset enable sub-10mV regulation error at point-of-load despite PCB IR drop |
| OPTI-LOOP® compensation | Transconductance error amplifier (gm = 4–6 mmho) with 3MHz GBW enables stable loop response with minimal COUT |
| Programmable protection | Adjustable UVLO via UVADJ pin; short-circuit latch-off timer set by RUN/SS capacitor; overvoltage soft-latch prevents rail collapse |
Applications
| Desktop Server VRM | High-Performance Notebook CPU Power |
|---|---|
Use Scenario: 12V input to 1.35V/55A core supply for dual-socket Xeon platform with strict transient response and thermal constraints. IC Role / Device Role / Timing Role: Primary 3-phase buck controller managing parallel MOSFET stages, synchronizing via PLLIN to system clock, and performing differential sensing at CPU socket. Use Value: ±5% current matching ensures uniform thermal loading across three inductors and MOSFETs, reducing hot-spot risk and enabling compact 6-layer board layout. |
Use Scenario: Slim-profile notebook requiring quiet, efficient 1.0V/30A GPU core supply with minimal acoustic noise and no burst-mode ripple. IC Role / Device Role / Timing Role: Fixed-frequency 3-phase controller operating in Stage Shedding™ mode to maintain constant switching frequency down to 1A load while suppressing audible coil whine. Use Value: Eliminates light-load frequency modulation, preserving EMI filter integrity and avoiding interference with Wi-Fi/Bluetooth bands. |
| High-Output Industrial DC/DC Module | Multi-Rail Telecom Board Power |
Use Scenario: 48V-to-3.3V/80A intermediate bus converter feeding downstream POL regulators in base station equipment. IC Role / Device Role / Timing Role: High-current PolyPhase® controller delivering low-impedance 3.3V rail with remote sensing across backplane connectors to compensate for inter-board voltage drop. Use Value: Differential amplifier rejects common-mode noise from shared ground planes, ensuring ±1% regulation accuracy despite 50mΩ interconnect resistance. |
Use Scenario: 12V input powering multiple isolated rails (1.8V, 2.5V, 3.3V) on telecom line card with strict sequencing and fault isolation. IC Role / Device Role / Timing Role: Master controller generating CLKOUT signal to synchronize secondary LTC3731-based converters, enabling deterministic phase alignment across all rails. Use Value: Reduces total input capacitance requirement by >80% versus single-phase designs, lowering board area and cost of high-reliability tantalum/Ceramic stacks. |
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 |
|---|---|---|---|
| MP8765GL-10-Z | Integrated power stage (60A max), fixed 500kHz freq, no PLL sync or differential sensing | Targeted at space-constrained consumer devices; lacks remote sensing and multi-controller synchronization | Select when board area is critical and system-level sync/differential sensing not required |
| LTC3833EGN#PBF | Single-phase controller, 0.6V–24V VOUT, no Stage Shedding™, lower max freq (850kHz) | Used in lower-current, non-interleaved designs; requires three copies + external logic for 3-phase emulation | Select only if 3-phase integration is unnecessary and discrete phase control is preferred |
Compared with MP8765GL-10-Z and LTC3833EGN#PBF, the LTC3731CG#TRPBF uniquely combines true 3-phase interleaving, differential remote sensing, and programmable multi-mode light-load operation-making it the only choice for high-accuracy, high-current server VRMs requiring thermal balance and system-level timing coordination.
Availability
LTC3731CG#TRPBF is available at Aetrix Electronics and suitable for desktop server VRMs, high-performance notebook CPU/GPU power delivery, and industrial high-output DC/DC modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3731CG#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 legacy Linear ICs including the LTC3731 series.
The LTC3731 belongs to Linear's PolyPhase® controller family, designed specifically for high-efficiency, high-current, multi-phase DC/DC conversion in computing and communications infrastructure where thermal management, transient response, and board-level power integrity are critical.
FAQ
What is the maximum output current supported by the LTC3731CG#TRPBF?
The LTC3731CG#TRPBF itself does not define a hard current limit-it controls external N-MOSFETs whose current capability depends on layout, cooling, and FET selection. In the typical application (Figure 1), it delivers 55A at 1.35V using 0.003Ω sense resistors and 0.8µH inductors. Designers scale output current by adjusting RSENSE, inductor DCR, and MOSFET RDS(on) while respecting the ±5% phase-matching spec and thermal limits of the 36-pin SSOP package.
Does the LTC3731CG#TRPBF support remote voltage sensing?
Yes, the LTC3731CG#TRPBF supports true differential remote sensing via dedicated IN+ and IN– pins connected directly to the load terminals. Its integrated precision differential amplifier (gain = 0.995–1.005 V/V, offset <5mV) rejects PCB ground noise and compensates for voltage drop across interconnects-enabling ±1% output regulation accuracy even with 50mΩ path resistance, as confirmed in the Electrical Characteristics table and Functional Diagram.
How does the Stage Shedding™ mode work in the LTC3731CG#TRPBF?
In Stage Shedding™ mode (enabled by tying FCB to VCC), the LTC3731CG#TRPBF disables two of three phases below ~10% of full load, leaving only Phase 1 active in discontinuous conduction mode. This eliminates gate drive and switching losses from inactive phases while maintaining fixed-frequency operation and low-noise performance. Below 1% load, further cycle skipping occurs to sustain regulation-distinct from Burst Mode®, which introduces variable-frequency operation.
Can the LTC3731CG#TRPBF be synchronized to an external clock source?
Yes, the LTC3731CG#TRPBF supports external synchronization via the PLLIN pin, which accepts TTL/CMOS-compatible clock signals. The internal phase-locked loop aligns Controller 1's TG1 rising edge to the PLLIN rising edge, enabling precise phase alignment across multiple LTC3731CG#TRPBF units or other PolyPhase® controllers. The PLLFLTR pin provides both filtered phase detector output and direct DC voltage control of oscillator frequency (250–600kHz).
What protection features are built into the LTC3731CG#TRPBF?
The LTC3731CG#TRPBF integrates short-circuit protection with a defeatable timed shutdown (via RUN/SS capacitor), overvoltage soft-latch, current foldback limiting, adjustable undervoltage lockout (UVADJ pin), and thermal shutdown (>125°C junction). It also features PGOOD monitoring with 100µs fault delay and ±10% window detection, plus differential amplifier-based output validation that enhances reliability in noisy environments.
LTC3731CG#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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
LTC3731CG#TRPBF FAQ
1.How can I place an order for LTC3731CG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3731CG#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 LTC3731CG#TRPBF reliable?
The price and inventory of LTC3731CG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3731CG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3731CG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3731CG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3731CG#TRPBF?
LTC3731CG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3731CG#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 LTC3731CG#TRPBF?
For technical support, including LTC3731CG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3731CG#TRPBF requirements.
6.How does Aetrix verify that LTC3731CG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3731CG#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 LTC3731CG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3731CG#TRPBF?
All LTC3731CG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3731CG#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 LTC3731CG#TRPBF part is unused and in its original packaging.
Return procedure for LTC3731CG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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