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Analog Devices Inc. LTC3731HG#PBF
- Part No.:
- LTC3731HG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC3731HG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,492
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Product details
Overview
LTC3731HG#PBF 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% per-phase current matching, operates up to 680kHz per phase, and supports junction temperatures up to 140°C - ideal for high-current CPU/GPU core power supplies in industrial and automotive systems.
For engineers reviewing the LTC3731HG#PBF datasheet, LTC3731HG#PBF pinout, LTC3731HG#PBF application, or LTC3731HG#PBF equivalent, key selection considerations include its 3-phase phase-locked architecture, Stage Shedding™/Burst Mode® light-load optimization, ±2% VREF accuracy over temperature, and support for 36-pin SSOP or 32-pin QFN packages with validated thermal performance up to 140°C.
Technical Context
The LTC3731HG#PBF implements a constant-frequency, current-mode control loop with three independent PWM channels synchronized at 120° phase separation. Each channel features dedicated differential current sense inputs (SENSE1±–SENSE3±), adjustable ITH-based peak current threshold, and precision 0.6V reference with ±2% tolerance over –40°C to 140°C.
Its PLL architecture accepts external synchronization via PLLIN and allows frequency tuning from 225kHz to 680kHz per phase using the PLLFLTR voltage (0–2.4V). The controller integrates OPTI-LOOP® compensation, short-circuit foldback protection, and programmable undervoltage lockout via UVADJ - all while maintaining stable operation under transient load steps up to 50A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 3-phase synchronous buck controller - enables tripled effective switching frequency for reduced input/output ripple and improved transient response. |
| Switching Frequency Range | 225kHz to 680kHz per phase - adjustable via PLLFLTR voltage; supports phase-locking to external clock for multi-controller synchronization. |
| Output Voltage Range | 0.6V to 6V - set by external resistor divider on EAIN; ±2% reference accuracy ensures tight regulation across full temperature range. |
| Current Sensing Threshold | 65mV to 90mV (typ. 75mV) - differential sense input with ±5% worst-case match between phases for balanced thermal loading. |
| Junction Temperature Range | –40°C to +140°C - rated for harsh environments; thermal shutdown activates above 160°C with derated lifetime above 125°C. |
| Operating Supply Voltage (VCC) | 4.5V to 7V - powers internal logic and gate drivers; requires low-ESR local decoupling to PGND for stable high-current drive. |
| Power Good Accuracy | ±10% output window with 100µs fault delay - provides reliable system-level power sequencing and fault reporting. |
Pinout & Package
Package: 36-lead narrow (0.209") plastic SSOP (G package), exposed pad not present; thermal resistance θJA = 70°C/W, θJC = 25°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| TG1–TG3 | Top gate drivers | Floating high-side N-MOSFET drivers with bootstrapped supply; require external Schottky diode and capacitor per phase. |
| BG1–BG3 | Bottom gate drivers | Ground-referenced N-MOSFET drivers; connect directly to MOSFET sources and PGND for low-inductance return path. |
| SENSE1±–SENSE3± | Differential current sense inputs | Measure voltage drop across external RSENSE; enable per-phase current limiting and matching within ±5% error. |
| EAIN | Error amplifier input | Receives feedback from output voltage divider; compared to 0.6V internal reference to regulate output voltage. |
| ITH | Error amplifier output / compensation node | Controls peak inductor current per phase; used for loop compensation and current foldback activation during overload. |
| PLLIN / PLLFLTR | Phase-lock interface | PLLIN accepts external sync signal; PLLFLTR sets oscillator frequency (225–680kHz) or receives phase detector output. |
| RUN/SS | Soft-start & short-circuit timer | Capacitor sets ramp time and latch-off timeout; discharges during output short to initiate shutdown after configurable delay. |
| PGOOD | Open-drain power-good indicator | Asserts low when output deviates >±10% for ≥100µs; used for system enable/disable sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| 3-Phase Phase-Locked Architecture | 120° inter-phase timing reduces RMS input/output capacitor current by ~58%, lowering thermal stress and component size. |
| Stage Shedding™ Operation | Disables two phases below ~10% load, eliminating gate charge and switching losses of inactive stages to maximize light-load efficiency. |
| Burst Mode® Regulation | Reduces switching frequency and disables synchronous rectification at light loads, minimizing quiescent current without sacrificing regulation. |
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing loop stability across wide load and line variations - reduces BOM cost and board area. |
| ±5% Per-Phase Current Matching | Ensures even thermal distribution across MOSFETs and inductors, enabling smaller magnetics and lower system-level cooling requirements. |
Applications
| Server CPU Core Power | Automotive ADAS Domain Controller |
|---|---|
|
Use Scenario: Delivering 1.35V/55A to high-performance x86 CPU cores under dynamic 0–50A load transients. IC Role / Device Role / Timing Role: 3-phase synchronous buck controller managing three parallel power stages with 120° phase shift and PLL synchronization. Use Value: Tripled effective switching frequency improves transient response; ±5% current matching prevents thermal hotspots in compact PCB layouts. |
Use Scenario: Providing stable 1.8V/30A supply to radar processing SoC in vibration-prone vehicle cabin environments. IC Role / Device Role / Timing Role: High-temperature-rated controller operating up to 140°C junction, with programmable UVLO and PGOOD sequencing for ASIL-B compliance. Use Value: Guaranteed operation to 140°C eliminates need for external thermal derating; ±2% VREF accuracy maintains SoC voltage margin across automotive temperature extremes. |
| Industrial PLC I/O Module | High-Density Telecom Board Power |
|
Use Scenario: Generating 3.3V/20A for FPGA and analog front-end in DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: Multi-phase controller with Stage Shedding™ to maintain >85% efficiency from 100mA to full load in convection-cooled enclosure. Use Value: Discontinuous operation at light loads eliminates audible noise and EMI spikes common with burst-mode converters in sensitive measurement circuits. |
Use Scenario: Consolidating multiple point-of-load rails into single high-current 12V→0.9V converter on space-constrained 5G baseband board. IC Role / Device Role / Timing Role: Synchronizable 3-phase controller enabling precise interleaving with adjacent DC/DC modules to suppress input ripple and EMI. Use Value: CLKOUT pin allows daisy-chained synchronization of up to 12 phases; reduces input capacitor count by 90% vs. single-phase implementation. |
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-PR | 4-phase controller with integrated MOSFET drivers; max 120°C junction rating; no Stage Shedding™ mode. | Targeted at mid-power server VRMs where integration reduces layout complexity but thermal headroom is lower. | Select MP2940AGQ-PR when board space is constrained and 120°C operation suffices; avoid if 140°C ambient or Stage Shedding™ efficiency is required. |
| ISL95812IRZ | 3-phase controller with digital interface (SVID); supports adaptive voltage positioning; 105°C max junction rating. | Designed for Intel-compatible mobile CPU power delivery with dynamic VID updates; lacks analog PLLIN sync capability. | Select ISL95812IRZ only for SVID-compliant platforms requiring AVP; LTC3731HG#PBF remains preferred for analog-synchronized, high-temp industrial use. |
Compared with MP2940AGQ-PR and ISL95812IRZ, the LTC3731HG#PBF uniquely combines 140°C operation, analog PLL synchronization, and Stage Shedding™ - making it the only option qualified for extended-life industrial and under-hood automotive applications demanding both thermal robustness and analog timing control.
Availability
LTC3731HG#PBF is available at Aetrix Electronics and suitable for high-current CPU/GPU power supplies, automotive ADAS domain controllers, and industrial PLC I/O modules requiring stable component supply with long-term lifecycle assurance.
Supply support for LTC3731HG#PBF 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 LTC3731H family.
The LTC3731H series was designed specifically for high-efficiency, high-current multiphase DC/DC conversion in thermally demanding environments - emphasizing precision current matching, wide temperature operation, and flexible light-load control modes.
FAQ
What is the maximum operating junction temperature for the LTC3731HG#PBF?
The LTC3731HG#PBF is rated for continuous operation up to 140°C junction temperature, with thermal shutdown activating above 160°C. Its G-package SSOP construction achieves θJA = 70°C/W and θJC = 25°C/W, enabling reliable deployment in automotive engine compartments and industrial enclosures without forced air cooling. This rating is confirmed in the Absolute Maximum Ratings table and validated across production lots.
Does the LTC3731HG#PBF support synchronization with external clock sources?
Yes, the LTC3731HG#PBF supports full phase-lock synchronization via its PLLIN pin, which accepts TTL/CMOS-compatible clock signals. The internal phase detector compares PLLIN's rising edge to TG1's rising edge and adjusts oscillator frequency via PLLFLTR to achieve zero-phase error. This capability enables precise interleaving across multiple LTC3731HG#PBF controllers or with other PolyPhase® devices - critical for EMI reduction in dense power systems.
How does Stage Shedding™ operation improve efficiency in the LTC3731HG#PBF?
Stage Shedding™ in the LTC3731HG#PBF disables two of three output phases when load drops below ~10% of full scale, eliminating gate drive and switching losses from inactive channels. At very light loads (<1%), it further skips cycles while maintaining regulation - achieving higher light-load efficiency than Burst Mode® alone. This behavior is activated by tying the FCB pin to VCC and is documented in the Applications section of the datasheet.
What are the key differences between the LTC3731HG#PBF and LTC3731HUH#PBF packages?
The LTC3731HG#PBF uses a 36-pin narrow SSOP package (θJA = 70°C/W), while the LTC3731HUH#PBF uses a 32-pin 5mm × 5mm QFN (θJA = 34°C/W). The QFN offers superior thermal performance but shares identical electrical specifications, pin functions, and operating temperature range (–40°C to 140°C). Pin 33 in the UH package is the exposed thermal pad tied to SGND; pins 1, 2, and 32 must remain unconnected.
Can the LTC3731HG#PBF be used in applications requiring ±10% output voltage tolerance?
Yes - the LTC3731HG#PBF's PGOOD pin provides a dedicated open-drain output that asserts low when output voltage deviates beyond ±10% of nominal for ≥100µs. This feature is fully specified in the Electrical Characteristics table (VPGTHNEG/VPGTHPOS = ±7% to ±13%) and is used for system-level power sequencing, fault detection, and safe startup/shutdown protocols in mission-critical designs.
LTC3731HG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 36-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- 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 ~ 140°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
LTC3731HG#PBF FAQ
1.How can I place an order for LTC3731HG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3731HG#PBF 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 LTC3731HG#PBF reliable?
The price and inventory of LTC3731HG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3731HG#PBF is usually 5 days.
3.What payment methods are accepted for LTC3731HG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3731HG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3731HG#PBF?
LTC3731HG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3731HG#PBF 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 LTC3731HG#PBF?
For technical support, including LTC3731HG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3731HG#PBF requirements.
6.How does Aetrix verify that LTC3731HG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3731HG#PBF 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 LTC3731HG#PBF meets industry standards.
7.What is the process for return or replacement of LTC3731HG#PBF?
All LTC3731HG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3731HG#PBF, 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 LTC3731HG#PBF part is unused and in its original packaging.
Return procedure for LTC3731HG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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