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Analog Devices Inc. LTC3729EUH#PBF
- Part No.:
- LTC3729EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3729EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:169
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Product details
Overview
LTC3729EUH#PBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down current-mode controller IC designed for high-current DC/DC conversion in server and computing power supplies. It delivers up to 40A output at 1.6V with ±1% voltage accuracy, operates from 4V–36V input, supports phase-lockable fixed-frequency switching from 250kHz to 550kHz, and integrates true remote differential sensing for precision regulation in high-current PCB layouts.
For engineers reviewing the LTC3729EUH#PBF datasheet, LTC3729EUH#PBF pinout, LTC3729EUH#PBF application, or LTC3729EUH#PBF equivalent, key selection considerations include its 2-phase PolyPhase® architecture, OPTI-LOOP® compensation for wide COUT/ESR tolerance, integrated power-good indicator, 99% dropout duty cycle, and compatibility with external N-channel MOSFETs in high-efficiency, thermally optimized multi-phase designs.
Technical Context
The LTC3729EUH#PBF implements a constant-frequency, current-mode control architecture with two independent synchronous buck channels operating 180° out of phase. Its internal differential amplifier enables true remote sensing across both VOUT+ and VOUT− terminals, critical for maintaining regulation under high-current PCB trace drops.
It features a phase-locked loop (PLL) with programmable frequency range (250–550kHz), configurable phase offset via PHASMD pin, and CLKOUT signal for daisy-chaining up to 12 controllers. The ITH pin serves as unified error amplifier output and current threshold control point, while RUN/SS provides combined soft-start timing and short-circuit timeout functionality.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 36V - supports wide-range industrial and server input rails including 5V, 12V, and 24V systems. |
| Output Voltage Accuracy | ±1% over line, load, and temperature - ensures stable core voltage delivery for CPUs/FPGAs without external calibration. |
| Switching Frequency | 250kHz to 550kHz (phase-lockable) - balances efficiency vs. component size; 2-phase operation yields effective 1.1MHz ripple cancellation. |
| Duty Cycle Max | 99.5% - enables ultra-low dropout operation down to VOUT ≈ VIN − 0.3V, critical for point-of-load regulation near supply rails. |
| Current Sense Threshold | 65mV typical (max 85mV) - sets peak inductor current; enables precise current sharing between phases with external RSENSE. |
| Power Good Threshold | ±7.5% of setpoint - provides reliable system-level power sequencing and fault detection with <10µs response. |
| Thermal Resistance θJA | 34°C/W (QFN package) - enables high-power density layout with minimal heatsinking in compact 5mm × 5mm footprint. |
Pinout & Package
Package: 32-lead 5mm × 5mm plastic QFN (UH); exposed pad soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS (Pin 2) | Soft-start timer & shutdown control | Capacitor-based ramp controls ITH startup; also discharges during output collapse to trigger short-circuit latchoff after user-defined timeout. |
| SENSE1+/SENSE1− (Pins 1,31) | Differential current sense inputs (Channel 1) | Measure voltage drop across external RSENSE to regulate peak inductor current; common-mode range extends to 1.1×INTVCC. |
| ITH (Pin 5) | Error amplifier output & current threshold control | 0–2.4V analog control voltage that simultaneously sets both channel current limits and regulates output voltage via EA servo loop. |
| TG1/TG2 (Pins 14,26) | Top N-MOSFET gate drivers | Floating high-side drivers with INTVCC-referenced swing; support bootstrap operation up to 42V BOOST-SW rating. |
| BG1/BG2 (Pins 18,22) | Bottom N-MOSFET gate drivers | Ground-referenced drivers sourcing/sinking >5A peak; enable synchronous rectification for high-efficiency operation. |
| VDIFFOUT (Pin 7) | Differential amplifier output | Provides remote-sensed VOUT referenced to SGND; drives external resistor divider to EAIN for accurate feedback despite PCB IR drop. |
| CLKOUT (Pin 27) | Phase-synchronized clock output | Drives PLLIN of additional LTC3729 controllers to expand system to 12 phases with evenly spaced timing for optimal ripple cancellation. |
Key Features
| Feature | Design Value |
|---|---|
| PolyPhase® dual-channel architecture | Two 180°-out-of-phase buck stages reduce RMS input/output capacitor ripple by >70%, enabling smaller, lower-cost bulk capacitance. |
| OPTI-LOOP® compensation | Allows stable loop response across wide ranges of output capacitance (10µF–10,000µF) and ESR (0.5mΩ–100mΩ), simplifying design for diverse load profiles. |
| True remote differential sensing | Internal differential amplifier (ADA = 1.00±0.5%, CMRR ≥46dB) measures VOUT+ and VOUT− directly, eliminating regulation error from PCB trace resistance. |
| Integrated power-good indicator | Open-drain PGOOD asserts low when EAIN deviates >±7.5% from 0.8V reference - provides deterministic system power sequencing without external comparators. |
| Programmable phase offset & synchronization | PHASMD pin selects 180° or 240° inter-channel phase; PLLIN accepts external clock to lock all phases to master system timing source. |
Applications
| High-Performance Server VRM | AI Accelerator Power Delivery |
|---|---|
Use Scenario: Regulating 1.2V/60A core voltage for dual-socket Xeon Scalable processors with tight transient requirements. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing parallel MOSFET stages with interleaved timing to minimize input ripple and improve dynamic response. Use Value: 1.1MHz effective ripple frequency reduces required input bulk capacitance by 4× versus single-phase; ±1% accuracy maintains CPU stability under load-line modulation. |
Use Scenario: Delivering 0.8V/80A to GPU or AI ASIC with sub-100ns load-step response and <1% droop. IC Role / Device Role / Timing Role: Phase-locked PolyPhase® controller coordinating four LTC3729EUH#PBF units (8 total phases) for ultra-low-noise, high-bandwidth power delivery. Use Value: Distributed current sensing and remote feedback ensure <±5mV regulation at point-of-load despite 50mΩ board trace resistance; CLKOUT daisy-chain enables deterministic multi-controller timing alignment. |
| Industrial High-Current DC Distribution | Telecom Baseband Processing |
Use Scenario: Converting 24V intermediate bus to 3.3V/30A for FPGA-based signal processing modules in ruggedized enclosures. IC Role / Device Role / Timing Role: Dual-phase controller operating at 350kHz with external EXTVCC supply to maximize efficiency and minimize thermal stress in convection-cooled environments. Use Value: 99.5% max duty cycle sustains regulation down to 24.2V input; INTVCC/EXTVCC switchover reduces driver losses by bypassing internal LDO when VOUT ≥ 4.7V. |
Use Scenario: Providing tightly regulated 1.8V/25A supply to multi-core baseband SoC in 5G radio units with strict EMI limits. IC Role / Device Role / Timing Role: Synchronous buck controller using phase-locked 480kHz operation and spread-spectrum-capable PLLFLTR voltage to suppress narrowband emissions. Use Value: Interleaved switching reduces fundamental EMI amplitude by 12dB; PGOOD output interfaces directly to FPGA reset controller for safe power-up sequencing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2940AGQ-Z | Fixed 500kHz frequency only; no PLLIN/CLKOUT sync capability; integrated MOSFET drivers rated for ≤30A total. | Lacks PolyPhase® expansion beyond 2 phases; limited to mid-power applications where daisy-chaining is unnecessary. | Select when board space is constrained and multi-controller synchronization is not required; verify thermal margin at full load. |
| ISL95812IRZ | Supports 3-phase operation natively; includes digital interface (SMBus) for telemetry; higher quiescent current (1.2mA vs 0.58mA). | Targets advanced VRM systems requiring real-time current/voltage reporting and adaptive phase shedding. | Choose for digitally managed power systems needing PMBus communication; avoid if analog-only control and minimal BOM count are priorities. |
Compared with MP2940AGQ-Z and ISL95812IRZ, the LTC3729EUH#PBF uniquely combines analog PLL synchronization, true remote sensing, and seamless 2-to-12 phase scalability - making it optimal for high-reliability, high-current analog power architectures where deterministic timing and regulation fidelity outweigh digital telemetry needs.
Availability
LTC3729EUH#PBF is available at Aetrix Electronics and suitable for high-current server VRMs, AI accelerator power delivery, and industrial DC distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3729EUH#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 all Linear power management ICs.
The LTC3729EUH#PBF belongs to Linear's high-performance PolyPhase® controller family, engineered specifically for multi-phase, high-current DC/DC conversion in datacenter, telecom, and industrial computing applications demanding precision regulation and thermal efficiency.
FAQ
What is the maximum output current achievable with a single LTC3729EUH#PBF controller?
A single LTC3729EUH#PBF supports dual-phase operation with external N-channel MOSFETs capable of delivering up to 40A continuous output (e.g., 1.6V/40A in the典型 application). Current capacity depends on MOSFET selection, thermal design, and PCB copper area - the controller itself regulates two independent phases with matched current sensing and timing. The LTC3729EUH#PBF does not limit current; it precisely controls gate drive timing and current thresholds to enable robust high-current delivery.
Does the LTC3729EUH#PBF require external components for phase synchronization across multiple controllers?
No - the LTC3729EUH#PBF includes built-in PLL circuitry and dedicated pins (PLLIN, CLKOUT, PHASMD) to synchronize multiple units without external logic. CLKOUT from one LTC3729EUH#PBF drives PLLIN of the next, and PHASMD configures relative phase offsets (180° or 240°). This native PolyPhase® expansion supports up to 12 synchronized controllers for systems requiring 15A–200A, eliminating need for external clock generators or timing ICs.
How does the RUN/SS pin function differently during startup versus fault conditions in the LTC3729EUH#PBF?
During startup, the RUN/SS pin charges an external capacitor to control soft-start ramp rate and delay full ITH activation until 1.5V is reached. During operation, the same capacitor discharges if output voltage falls below 70% of nominal - converting into a timed short-circuit shutdown. The LTC3729EUH#PBF thus reuses the same RC network for two distinct functions: controlled turn-on and intelligent fault timeout, reducing component count while maintaining safety.
Can the LTC3729EUH#PBF operate with only one phase active, and what design changes are needed?
Yes - the LTC3729EUH#PBF can be configured for single-phase operation by leaving one channel unpopulated and tying unused SENSE, TG, BG, SW, and BOOST pins appropriately (e.g., SENSE2± to SGND, TG2/BG2 open). The controller automatically disables unused channel circuitry. However, phase-interleaving benefits (ripple reduction, thermal spreading) are lost, and maximum output current is halved unless MOSFET sizing compensates. The LTC3729EUH#PBF remains fully functional in this mode with identical control loop behavior per active phase.
What is the role of the VDIFFOUT pin in the LTC3729EUH#PBF, and why is it essential for high-current designs?
The VDIFFOUT pin outputs the amplified difference between VOS+ and VOS− - providing a ground-referenced representation of true output voltage measured directly at the load terminals. In high-current designs, PCB trace resistance causes significant IR drop between regulator output and load; using VDIFFOUT for feedback (via resistive divider to EAIN) eliminates this error. The LTC3729EUH#PBF's differential amplifier achieves 46dB CMRR and 0.995–1.005 gain accuracy, ensuring <±1mV regulation error even with 50mΩ interconnect resistance.
LTC3729EUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 36V
- Frequency - Switching:
- 260kHz ~ 550kHz
- Duty Cycle (Max):
- 99.5%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Phase Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3729EUH#PBF FAQ
1.How can I place an order for LTC3729EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3729EUH#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 LTC3729EUH#PBF reliable?
The price and inventory of LTC3729EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3729EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3729EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3729EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3729EUH#PBF?
LTC3729EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3729EUH#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 LTC3729EUH#PBF?
For technical support, including LTC3729EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3729EUH#PBF requirements.
6.How does Aetrix verify that LTC3729EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3729EUH#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 LTC3729EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3729EUH#PBF?
All LTC3729EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3729EUH#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 LTC3729EUH#PBF part is unused and in its original packaging.
Return procedure for LTC3729EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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