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Analog Devices Inc. LTC3731HG#TRPBF
- Part No.:
- LTC3731HG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC3731HG#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,432
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Product details
Overview
LTC3731HG#TRPBF from Analog Devices (formerly Linear Technology) is a 3-phase, synchronous buck switching regulator controller designed for high-current DC/DC conversion in automotive and industrial power supplies. It drives three external N-channel MOSFET stages with 120° phase separation, operates up to 680kHz per phase, supports 0.6V–6V output voltage, delivers ±5% current matching across phases, and is rated for –40°C to 140°C junction temperature.
For engineers reviewing the LTC3731HG#TRPBF datasheet, LTC3731HG#TRPBF pinout, LTC3731HG#TRPBF application, or LTC3731HG#TRPBF equivalent, key selection considerations include phase-lockable fixed-frequency operation, Stage Shedding™/Burst Mode® light-load optimization, OPTI-LOOP® compensation, ±2% VREF accuracy over full temperature range, and support for up to 12-phase expansion via CLKOUT and PHASMD.
Technical Context
The LTC3731HG#TRPBF implements a constant-frequency, current-mode control architecture with three independent PWM channels, each featuring dedicated differential current sense inputs (SENSE1±, SENSE2±, SENSE3±), floating top-gate drivers (TG1–TG3), and synchronous bottom-gate drivers (BG1–BG3). Its PLL circuit synchronizes to external clocks via PLLIN and enables frequency tuning from 225kHz to 680kHz through the PLLFLTR pin voltage.
It integrates precision error amplification (gm = 3–7 mmho), adjustable soft-start (via RUN/SS capacitor), overvoltage soft-latch, short-circuit foldback protection, and programmable undervoltage lockout (UVADJ threshold = 1.13–1.23V). The device supports three operating modes-continuous PWM, Stage Shedding™, and Burst Mode®-selected by FCB pin voltage, with ITH serving as the unified compensation node for all three phases.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 3-phase synchronous buck controller with 120° phase interleaving |
| Switching Frequency Range | 225kHz to 680kHz per phase, adjustable via PLLFLTR voltage (0V–2.4V) |
| Output Voltage Range | 0.6V to 6V, set by external resistor divider on EAIN, ±2% reference accuracy up to 140°C |
| Current Sensing | Differential inputs per phase (SENSE1±/2±/3±); max threshold 65–90mV, ±5% worst-case match across phases |
| Junction Temperature Range | –40°C to 140°C, with thermal shutdown active above TJ > 160°C |
| Protection Features | Current foldback, overvoltage soft latch, undervoltage lockout (UVADJ), short-circuit latchoff with RUN/SS timeout |
| Package | 36-pin narrow SSOP (G package), exposed pad not present; θJA = 70°C/W, θJC = 25°C/W |
Pinout & Package
Package: 36-lead plastic SSOP (G package), 0.209" width, no exposed thermal pad. Pin pitch: 0.025", body dimensions: 9.9mm × 3.9mm × 1.75mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main supply input | Supplies internal logic and gate drivers; requires local 0.1µF decoupling to PGND |
| PGND | Power ground return | Direct connection point for bottom MOSFET sources and CIN (–) terminal |
| TG1–TG3 | Top N-channel gate drivers | Floating outputs driving external high-side MOSFET gates; swing = BOOSTx – SWx |
| BG1–BG3 | Bottom N-channel gate drivers | Ground-referenced outputs driving low-side MOSFET gates; swing = 0V to VCC |
| SW1–SW3 | Switch node connections | Connects to inductor high-side terminals; voltage swings from ~–0.3V to VIN |
| BOOST1–BOOST3 | Bootstrap supply pins | Connects to boot capacitors charged via external Schottky diodes; supplies floating top drivers |
| SENSE1±–SENSE3± | Differential current sense inputs | Each pair monitors RSENSE voltage drop; sets per-phase peak current limit via ITH |
| ITH | Error amplifier output & compensation node | Common control voltage for all three current comparators; used for loop compensation |
| EAIN | Error amplifier inverting input | Receives scaled output voltage feedback; compared against 0.6V internal reference |
| RUN/SS | Soft-start, run enable & short-circuit timer | Capacitor sets ramp time and latchoff delay; discharges during output short-circuit |
| UVADJ | Programmable undervoltage lockout input | Threshold = 1.13–1.23V; disables drivers when voltage falls below this level |
| FCB | Forced continuous/burst/stage shedding mode select | Voltage < 0.6V → continuous; open → Burst Mode®; tied to VCC → Stage Shedding™ |
| PLLIN / PLLFLTR | Phase-locked loop sync input & frequency control | PLLIN accepts external clock; PLLFLTR voltage (0–2.4V) sets oscillator frequency |
| CLKOUT | Phase-synchronized clock output | Drives additional controllers for 6- or 12-phase systems; phase shift set by PHASMD |
| PGOOD | Open-drain power-good indicator | Pulls low if VOUT deviates >±10% for ≥100µs; no delay on assertion |
Key Features
| Feature | Design Value |
|---|---|
| 3-phase interleaved architecture | Reduces RMS input/output capacitor currents by ~58%, enabling smaller, cooler-filter designs |
| Stage Shedding™ mode | Disables two phases below ~10% load, eliminating gate charge and switching losses of inactive stages |
| Burst Mode® operation | Minimizes light-load quiescent current to ~50µA while maintaining tight output regulation and low ripple |
| OPTI-LOOP® compensation | Enables stable loop response with minimal output capacitance, reducing CO size and cost |
| ±5% inter-phase current matching | Ensures balanced thermal loading across MOSFETs and inductors, improving reliability and power density |
| Programmable phase shift (PHASMD) | Configures CLKOUT edge alignment (30° or 60°) to enable seamless 6- or 12-phase system expansion |
Applications
| High-Performance CPU/GPU Core Power | Automotive ADAS Domain Controller Supply |
|---|---|
Use Scenario: Delivering 55A at 1.35V to advanced microprocessors in server or AI accelerator boards with strict transient response requirements. IC Role / Device Role / Timing Role: 3-phase synchronous buck controller managing parallel power stages, providing fast load-step response via tripled effective switching frequency. Use Value: Achieves >90% efficiency at 45A with 8V input, reduces input capacitor RMS current by 90% versus single-phase, and maintains ±5% current balance across phases for uniform thermal distribution. |
Use Scenario: Powering radar, camera, and sensor fusion modules in autonomous driving ECUs requiring robust operation from –40°C to 140°C ambient. IC Role / Device Role / Timing Role: High-reliability multi-phase controller with integrated overtemperature protection, UVLO, and short-circuit latchoff for mission-critical automotive subsystems. Use Value: Supports AEC-Q100 stress testing via 140°C junction rating, uses Stage Shedding™ to maintain >85% efficiency at 1A standby load, and provides PGOOD signaling for system-level fault management. |
| Industrial PLC I/O Module Supply | Telecom Baseband Processor Rail |
Use Scenario: Generating stable 3.3V/20A output for programmable logic controllers exposed to wide ambient temperature swings and electrical noise. IC Role / Device Role / Timing Role: Noise-immune current-mode controller with differential sensing, PLL synchronization, and reduced EMI via phase interleaving. Use Value: Delivers ±2% output regulation over –40°C to 140°C, suppresses conducted noise via 120° phase offset, and enables synchronization to backplane clock using PLLIN. |
Use Scenario: Providing tightly regulated 1.2V/30A supply to 5G baseband SoCs where dynamic load steps exceed 20A/µs. IC Role / Device Role / Timing Role: Fast-transient 3-phase controller with OPTI-LOOP® compensation and 680kHz maximum per-phase frequency for minimized output impedance. Use Value: Reduces output voltage deviation to <15mV under 0→30A step (1.2V rail), cuts required COUT by 40% vs conventional compensation, and supports burst-mode idle states without audible noise. |
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-DC | Integrated 3-phase controller+driver in 5mm×5mm QFN; lacks PLL sync, Stage Shedding™, and 140°C rating (max 125°C) | Targeted at space-constrained telecom/datacom; no automotive temp grade or phase expansion capability | Choose MP2940AGQ-DC only if board area is critical and 125°C max junction suffices; LTC3731HG#TRPBF preferred for extended temp or multi-controller sync. |
| LTC3833EUH#TRPBF | Single-phase controller with similar 0.6V ref, 140°C rating, and Burst Mode®, but no multi-phase coordination or CLKOUT | Suitable for lower-current rails (<25A); cannot scale to 3-phase or higher without external timing coordination | Select LTC3833EUH#TRPBF for simpler, lower-cost single-rail designs; LTC3731HG#TRPBF required when >30A output or phase interleaving benefits are needed. |
Compared with MP2940AGQ-DC and LTC3833EUH#TRPBF, the LTC3731HG#TRPBF uniquely combines 140°C operation, hardware-based 3-phase interleaving with 120° offset, CLKOUT-driven scalability to 12 phases, and three distinct light-load modes - making it the only option qualified for high-reliability, thermally demanding, multi-phase industrial and automotive applications.
Availability
LTC3731HG#TRPBF is available at Aetrix Electronics and suitable for high-current CPU core supplies, automotive ADAS domain controllers, and industrial PLC I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3731HG#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, formed through the acquisition of Linear Technology in 2017.
The LTC3731HG#TRPBF belongs to ADI's PolyPhase® controller product line, engineered specifically for high-efficiency, high-current DC/DC conversion in thermally constrained environments such as automotive engine compartments and industrial control cabinets.
FAQ
What is the maximum operating junction temperature of the LTC3731HG#TRPBF?
The LTC3731HG#TRPBF is rated for continuous operation up to 140°C junction temperature, with overtemperature protection activating above 160°C. Its thermal resistance is θJA = 70°C/W and θJC = 25°C/W in the 36-pin SSOP package, enabling reliable use in automotive under-hood and industrial high-ambient applications where the LTC3731HG#TRPBF must sustain full load without derating.
How does the LTC3731HG#TRPBF achieve phase interleaving and what is its benefit?
The LTC3731HG#TRPBF internally generates three PWM signals with fixed 120° phase separation between TG1, TG2, and TG3 outputs. This interleaving reduces input and output capacitor RMS currents by up to 58%, lowers EMI, improves transient response, and allows smaller passive components - a key advantage realized in every LTC3731HG#TRPBF design versus single-phase alternatives.
Can the LTC3731HG#TRPBF be synchronized to an external clock source?
Yes, the LTC3731HG#TRPBF supports external synchronization via the PLLIN pin, which accepts a TTL/CMOS clock signal. Its internal phase-locked loop locks the rising edge of TG1 to the rising edge of the PLLIN signal, enabling precise timing coordination across multiple LTC3731HG#TRPBF controllers or with system master clocks - essential for noise-sensitive or deterministic timing applications.
What are the three light-load operating modes of the LTC3731HG#TRPBF and how are they selected?
The LTC3731HG#TRPBF offers Forced Continuous, Stage Shedding™, and Burst Mode® operation, selected by the FCB pin voltage: <0.6V → continuous; tied to VCC → Stage Shedding™; floating → Burst Mode®. Each mode optimizes efficiency and noise differently across load range - verified in the LTC3731HG#TRPBF datasheet Figures 20–23 - giving designers flexibility to match system requirements.
Does the LTC3731HG#TRPBF support output voltage tracking or sequencing?
No, the LTC3731HG#TRPBF does not integrate voltage tracking or sequencing circuitry. Its RUN/SS pin provides soft-start ramp control for a single output, and PGOOD indicates regulation status only. For multi-rail sequencing, external supervisors or discrete timing circuits must be used - a documented limitation confirmed in the LTC3731HG#TRPBF functional diagram and Applications Information section.
LTC3731HG#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 ~ 140°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
LTC3731HG#TRPBF FAQ
1.How can I place an order for LTC3731HG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3731HG#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 LTC3731HG#TRPBF reliable?
The price and inventory of LTC3731HG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3731HG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3731HG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3731HG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3731HG#TRPBF?
LTC3731HG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3731HG#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 LTC3731HG#TRPBF?
For technical support, including LTC3731HG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3731HG#TRPBF requirements.
6.How does Aetrix verify that LTC3731HG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3731HG#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 LTC3731HG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3731HG#TRPBF?
All LTC3731HG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3731HG#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 LTC3731HG#TRPBF part is unused and in its original packaging.
Return procedure for LTC3731HG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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