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Analog Devices Inc. LTC3861EUHE#TRPBF
- Part No.:
- LTC3861EUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-WFQFN Exposed Pad
- Datasheet:
-
LTC3861EUHE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,336
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Product details
Overview
LTC3861EUHE#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel, multiphase synchronous step-down voltage mode DC/DC controller designed for high-current distributed power systems. It supports 1–12-phase operation via parallel ICs, delivers ±0.75% output voltage regulation at 0.6V reference, operates from 3V–24V input to 0.6V–(VCC–0.5V) output, and features lossless DCR current sensing with accurate per-phase current sharing.
For engineers reviewing the LTC3861EUHE#TRPBF datasheet, LTC3861EUHE#TRPBF pinout, LTC3861EUHE#TRPBF application, or LTC3861EUHE#TRPBF equivalent, key selection criteria include its dual differential remote sense amplifiers, programmable 250kHz–2.25MHz switching frequency, prebiased load startup capability, and support for DrMOS/power block gate drivers in telecom and FPGA power delivery.
Technical Context
The LTC3861EUHE#TRPBF implements constant-frequency voltage mode control with two independent error amplifiers (COMP1/COMP2), each driving a PWM channel with dedicated FB/VSNSOUT/VSNSP/VSNSN pins for true remote differential output sensing. Its architecture integrates a high-bandwidth (40MHz unity-gain) differential amplifier per channel and a low-offset (±1.25mV) current sense amplifier supporting both DCR and precision resistor sensing.
It enables master-slave current sharing across up to six ICs using the IAVG pin and PHSMD-programmable phase alignment (120°/180°), while CLKIN/CLKOUT daisy-chaining allows synchronized multi-phase timing. The FREQ pin sources 20µA for resistor-programmed frequency or selects internal 600kHz/1MHz presets when CLKIN is low.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3V to 24V - supports wide-input industrial and telecom rails without external regulators. |
| VOUT Range | 0.6V to (VCC – 0.5V) - enables sub-1V core supplies for modern FPGAs and ASICs. |
| Switching Frequency | 250kHz to 2.25MHz - adjustable via FREQ resistor or external CLKIN for EMI optimization and size reduction. |
| Reference Voltage | ±0.75% at 0.6V - ensures tight output regulation critical for low-voltage digital loads. |
| Current Sense Accuracy | ±1.25mV input-referred offset - enables precise per-phase current matching in multiphase designs. |
| Operating Temp | –40°C to 125°C junction - qualified for industrial and extended-temperature embedded applications. |
| Package | 36-pin 5mm × 6mm QFN (UHE) - exposes thermal pad (Pin 37 = SGND) for efficient heat dissipation. |
Pinout & Package
The LTC3861EUHE#TRPBF is housed in a 36-pin, 5mm × 6mm plastic QFN package (UHE) with an exposed thermal pad (Pin 37) that must be soldered to PCB signal ground for rated thermal performance (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1, FB2 (Pins 1, 10) | Error amplifier inverting input | Connects to VSNSOUTx for closed-loop regulation; tying to VCC disables respective channel's error amp and COMP output. |
| VSNSP1/VSNSN1, VSNSP2/VSNSN2 (Pins 3,4,7,8) | Differential remote sense inputs | VSNSP connects to feedback divider midpoint; VSNSN to load ground - eliminates ground loop errors in high-current systems. |
| COMP1, COMP2 (Pins 2, 9) | Error amplifier output | Drives PWM duty cycle; low-impedance op-amp output - cannot be wired in parallel unless master-slave configured via FB tie-off. |
| PWM1, PWM2 (Pins 29, 18) | Top gate drive outputs | Three-state compatible signals for external gate drivers or DrMOS; minimum on/off times prevent shoot-through. |
| IAVG (Pin 32) | Average current monitor | Outputs voltage proportional to master-phase average current - used for inter-IC current sharing in multiphase configurations. |
| PHSMD (Pin 15) | Phase mode control | Selects CH1–CH2 phase relationship (120°/180°) and CH1–CLKOUT alignment - essential for interleaving up to 12 phases. |
Key Features
| Feature | Design Value |
|---|---|
| Dual differential remote sense amplifiers | Enables accurate output regulation at point-of-load despite PCB trace resistance and ground shifts. |
| Programmable soft-start / tracking (TRACK/SS1,2) | Supports controlled ramp-up of multiple rails with coincident or ratiometric sequencing for system-level power integrity. |
| Lossless DCR current sensing | Eliminates sense resistor losses and board space while maintaining ±1.25mV sensing accuracy for current sharing. |
| Prebiased load startup | Disables inductor current reversal during soft-start - prevents reverse current flow into powered-down downstream circuitry. |
| 128-cycle overcurrent fault counter | Provides robust short-circuit protection with hysteresis, avoiding nuisance trips during transient overload conditions. |
Applications
| Telecom Base Station Power | FPGA Core Supply |
|---|---|
Use Scenario: High-density 48V-to-12V intermediate bus conversion feeding multiple downstream POL modules in macrocell BTS. IC Role / Device Role / Timing Role: Dual-channel controller orchestrating 6-phase interleaved buck stages to deliver >100A at 1.2V with <±1% regulation. Use Value: Dual differential sensing maintains accuracy across long PCB runs; programmable frequency avoids sensitive RF bands. | Use Scenario: Dynamic voltage scaling for Xilinx Versal ACAP requiring tightly regulated 0.8V core rail with fast load transient response. IC Role / Device Role / Timing Role: Master-slave configured LTC3861EUHE#TRPBF pair delivering 60A with current sharing and 500kHz switching. Use Value: ±0.75% 0.6V reference and high-bandwidth error amps achieve <50mV droop under 30A/µs load steps. |
| Data Center ASIC Supply | Industrial Motor Control Logic |
Use Scenario: Point-of-load supply for NVIDIA GPU compute modules where thermal density demands high-efficiency, low-noise 0.75V rails. IC Role / Device Role / Timing Role: 12-phase configuration using six paralleled LTC3861EUHE#TRPBF controllers with CLKIN synchronization. Use Value: Interleaved phases reduce input/output ripple by √n, enabling smaller bulk capacitors and lower EMI filter cost. | Use Scenario: Isolated I/O and logic power for servo drives requiring clean 3.3V/5V rails immune to motor switching noise. IC Role / Device Role / Timing Role: Independent dual-output mode powering isolated gate driver bias and microcontroller core from shared 24V input. Use Value: Separate RUN1/RUN2 control allows staggered startup; TRACK/SS pins enable coordinated sequencing with main power stage. |
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 | Single-chip dual-phase controller with integrated MOSFET drivers; no external gate driver required. Lacks dual differential remote sense amplifiers. | Better suited for space-constrained designs where driver integration reduces BOM count, but less flexible for high-current DrMOS implementations. | Choose MP2940AGQ-Z when board area is critical and discrete gate drivers are undesirable; LTC3861EUHE#TRPBF preferred for >60A systems with DrMOS or power blocks. |
| ISL95812IRZ | Intel VR12.5-compliant dual-phase controller with SMBus interface; supports dynamic VID programming. No IAVG-based current sharing bus. | Targeted at CPU/GPU VRMs with strict Intel compliance requirements; lacks analog current sharing for custom multiphase expansion. | Choose ISL95812IRZ only for Intel-platform VRMs requiring VID control; LTC3861EUHE#TRPBF offers broader flexibility for non-Intel high-current applications. |
Compared with MP2940AGQ-Z and ISL95812IRZ, the LTC3861EUHE#TRPBF provides superior analog current sharing scalability (up to 12 phases), dual differential remote sensing for precision regulation, and full analog programmability - making it optimal for custom high-current telecom, FPGA, and industrial power systems where flexibility and accuracy outweigh integration convenience.
Availability
LTC3861EUHE#TRPBF is available at Aetrix Electronics and suitable for telecom base station power, FPGA core supply, data center ASIC supply, and industrial motor control logic requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3861EUHE#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 its high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3861EUHE#TRPBF belongs to Linear's PolyPhase® synchronous buck controller family, engineered specifically for high-current, multi-rail power delivery in telecom infrastructure, computing, and industrial systems demanding precision regulation and scalable phase count.
FAQ
What is the maximum number of phases supported by the LTC3861EUHE#TRPBF?
The LTC3861EUHE#TRPBF supports up to 12-phase operation by paralleling up to six identical ICs using CLKIN/CLKOUT daisy-chaining and PHSMD-configured phase alignment. Each LTC3861EUHE#TRPBF provides two phases, and inter-IC current sharing is maintained via the IAVG pin bus. This scalability enables >200A output capability while minimizing input/output ripple through interleaving.
Does the LTC3861EUHE#TRPBF support prebiased load startup?
Yes, the LTC3861EUHE#TRPBF safely powers prebiased loads by disabling inductor current reversal during soft-start. When TRACK/SS1 or TRACK/SS2 is used for soft-start, the controller actively prevents negative current flow into an already-powered output rail - a critical feature for hot-swap and system-level power sequencing where downstream circuits may be live before the controller powers up.
How does the LTC3861EUHE#TRPBF achieve accurate current sharing between phases?
The LTC3861EUHE#TRPBF achieves accurate current sharing using lossless inductor DCR sensing combined with an auxiliary current-sharing loop. Each phase's current sense amplifier feeds into an overcurrent comparator and an integrator that compares instantaneous current to the master-phase average voltage on the IAVG pin. This analog feedback adjusts individual duty cycles in real time, maintaining balance within ±3% across all phases even with component tolerances.
Can the LTC3861EUHE#TRPBF operate with both DrMOS and discrete MOSFETs?
Yes, the LTC3861EUHE#TRPBF is designed to drive both DrMOS modules and discrete N-channel MOSFETs via external gate drivers. Its three-state PWM outputs (PWM1/PWM2) interface directly with DrMOS enable inputs, while PWMEN1/PWMEN2 provide open-drain enable signals for non-three-state drivers. The controller's flexible gate drive architecture supports power block, DrMOS, and discrete FET solutions without redesign.
What is the purpose of the CONFIG pin on the LTC3861EUHE#TRPBF?
The CONFIG pin on the LTC3861EUHE#TRPBF configures line feedforward compensation gain to maintain consistent modulator response across varying VIN and switching frequencies. Tying CONFIG to VCC or SGND selects different internal multiplier settings - ensuring stable loop dynamics and optimal transient line regulation regardless of input voltage or frequency selection, which is essential for wide-input industrial power supplies.
LTC3861EUHE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 36-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- PWM Signal
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 3V ~ 5.5V
- Frequency - Switching:
- 250kHz ~ 3MHz
- Duty Cycle (Max):
- 91.5%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Phase Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QFN (5x6)
LTC3861EUHE#TRPBF FAQ
1.How can I place an order for LTC3861EUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3861EUHE#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 LTC3861EUHE#TRPBF reliable?
The price and inventory of LTC3861EUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3861EUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3861EUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3861EUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3861EUHE#TRPBF?
LTC3861EUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3861EUHE#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 LTC3861EUHE#TRPBF?
For technical support, including LTC3861EUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3861EUHE#TRPBF requirements.
6.How does Aetrix verify that LTC3861EUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3861EUHE#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 LTC3861EUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3861EUHE#TRPBF?
All LTC3861EUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3861EUHE#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 LTC3861EUHE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3861EUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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