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Analog Devices Inc. LTC3865EUH#PBF
- Part No.:
- LTC3865EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3865EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:124
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Product details
Overview
LTC3865EUH#PBF from Analog Devices (formerly Linear Technology) is a dual, 2-phase synchronous step-down DC/DC controller driving all-N-channel MOSFET stages. It delivers precise 1.5V/15A and 1.2V/15A outputs with 180° phase interleaving, 4.5V–38V input range, and up to 770kHz phase-lockable switching frequency-used in high-density server VRMs and telecom power distribution systems.
For engineers reviewing the LTC3865EUH#PBF datasheet, LTC3865EUH#PBF pinout, LTC3865EUH#PBF application, or LTC3865EUH#PBF equivalent, key selection criteria include dual-channel independent tracking/soft-start, VID-based output programming, RSENSE/DCR current sensing, OPTI-LOOP® compensation, and selectable Burst Mode®/pulse-skipping/continuous conduction operation.
Technical Context
The LTC3865EUH#PBF implements constant-frequency current-mode control with two independent 180° out-of-phase channels, each featuring a transconductance error amplifier (gm = 2.2 mmho), programmable current limit via ILIM pin, and internal 5V INTVCC regulator (4.8–5.2V). Its MODE/PLLIN pin supports synchronization to external clocks up to 770kHz while enabling mode selection between Burst Mode®, pulse-skipping, and forced continuous conduction.
It uses dual independent ITH pins for per-channel current threshold control, VOSENSE pins for remote feedback sensing, and TK/SS pins for soft-start ramping or voltage tracking. The device supports both resistor-based and pin-strapped (VID11/12/21/22) output voltage programming from 0.6V to 5V with ±1% typical accuracy over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-input industrial, telecom, and server supply rails without pre-regulation. |
| Switching Frequency | 250kHz to 770kHz - adjustable via FREQ pin current (7.5μA) and external resistor; phase-lockable for EMI reduction. |
| Output Voltage Range | 0.6V to 5.0V - set via VID pin strapping or external resistive divider; 9-point precision programming with ±1% typical tolerance. |
| Current Sensing | RSENSE or DCR - supports low-loss inductor-based sensing; max sense threshold configurable from 24mV to 82mV via ILIM pin. |
| Efficiency | Up to 95% - achieved via dual-phase interleaving, N-channel synchronous drive, and low RDS(on) gate drivers (TG RUP = 2.6Ω, BG RDOWN = 1.4Ω). |
| Thermal Performance | θJA = 34°C/W - enabled by 5mm × 5mm QFN package with exposed SGND pad soldered to PCB for optimal heat dissipation. |
| Protection Features | Output overvoltage lockout (±10% trip), reverse current limiting, current foldback, and undervoltage lockout (3.3V on INTVCC with 0.55V hysteresis). |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed SGND pad (Pin 33), rated for –40°C to +125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOSENSE1, VOSENSE2 (Pins 1, 8) | Error amplifier feedback inputs | Accept remote-sensed output voltages; used with internal divider or external resistor network for regulation. |
| TK/SS1, TK/SS2 (Pins 2, 7) | Soft-start and tracking control | Internal 1.3μA current charges external capacitor for linear VOUT ramp; supports master-slave tracking via resistor divider. |
| ITH1, ITH2 (Pins 3, 6) | Error amplifier output / current threshold | Controls peak inductor current per channel; voltage range 0–2.7V sets current limit dynamically during transients. |
| VID11/12/21/22 (Pins 4, 5, 12, 28) | Output voltage programming inputs | Three-state logic (GND/FLOAT/INTVCC) selects one of nine preset output voltages from 0.6V to 5.0V. |
| ILIM (Pin 13) | Current sense threshold select | Tie to SGND/FLOAT/INTVCC to configure max sense voltage as 24/50/75mV (E-grade), enabling optimization for RSENSE or DCR sensing. |
| PGOOD (Pin 14) | Co-bonded power-good indicator | Open-drain output pulled low if either channel deviates >±10% from target after 100μs blanking time. |
| MODE/PLLIN (Pin 27) | Operating mode & sync input | Selects Burst Mode® (float), pulse-skipping (INTVCC), or forced continuous (GND); accepts external clock for synchronization. |
| FREQ (Pin 29) | Oscillator frequency set | 7.5μA constant current source; external resistor to SGND sets frequency from 250kHz to 770kHz. |
| TG1/TG2, BG1/BG2 (Pins 25/16, 23/19) | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6Ω pull-up / 1.5Ω pull-down; supports bootstrap operation up to 46V BOOST swing. |
| SW1/SW2 (Pins 26, 15) | Switch node connections | Connect to inductor high-side; voltage swings from Schottky drop below GND to VIN. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces input/output ripple current by ~70% vs single-phase, enabling smaller bulk capacitors and lower EMI. |
| OPTI-LOOP® compensation | Allows stable loop response across wide range of output capacitance (10μF–1000μF) and ESR (0.5mΩ–50mΩ) without redesign. |
| Independent track/soft-start | Enables controlled power-up sequencing between 1.5V and 1.2V rails, preventing bus contention in multi-rail systems. |
| Adjustable current limit | Three-level ILIM pin selection allows optimization for 2mΩ RSENSE, 0.5mΩ DCR, or ultra-low-loss designs without changing layout. |
| Output OV protection with reverse current limit | Prevents damage during load dump or hot-swap events; blocks reverse current flow at light loads to maintain efficiency. |
Applications
| Server VRM Power Delivery | Telecom Line Card Supplies |
|---|---|
Use Scenario: Dual-output CPU core and I/O rail generation in 1U rack servers with strict thermal and space constraints. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing 1.5V/15A and 1.2V/15A outputs with interleaved timing to minimize input ripple. Use Value: Achieves 95% peak efficiency and <10mV output ripple using compact 0.47μH inductors and ceramic output caps-reducing board area by 35% vs discrete solutions. | Use Scenario: Powering FPGA, DSP, and SerDes supplies on carrier-grade line cards requiring tight voltage accuracy and fast transient response. IC Role / Device Role / Timing Role: Precision voltage controller with VID programming and independent soft-start for coordinated rail bring-up across multiple ASICs. Use Value: ±1% output accuracy over –40°C to +125°C and <50μs recovery from 50% load step ensure signal integrity in high-speed serial links. |
| Industrial PLC Backplane | High-Density Data Center PSUs |
Use Scenario: Generating isolated 3.3V and 5V auxiliary rails from 24V backplane in modular PLC chassis with variable load profiles. IC Role / Device Role / Timing Role: Dual-channel controller operating in pulse-skipping mode to maintain >85% efficiency down to 5% load while supporting brown-out immunity. Use Value: Wide 4.5V–38V input range eliminates need for intermediate pre-regulators; UVLO hysteresis prevents chatter during input dips. | Use Scenario: Secondary-side regulation in 48V-to-12V/5V intermediate bus converters feeding distributed point-of-load regulators. IC Role / Device Role / Timing Role: High-frequency (770kHz) phase-locked controller synchronized to system clock to suppress beat frequencies in multi-module PSUs. Use Value: Phase-lock capability enables deterministic EMI placement and reduces filtering component count by 40% in multi-kW systems. |
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-DC | Single-chip dual-phase controller with integrated MOSFET drivers only; no VID programming; fixed 600kHz frequency. | Targeted at cost-sensitive consumer SSDs; lacks independent tracking, EXTVCC support, and Burst Mode®. | Choose MP2940AGQ-DC only when board space is critical and VID flexibility is unnecessary. |
| ISL95836IRZ | Intel VR12.5-compliant dual-phase controller with SMBus interface; supports dynamic VID updates; higher quiescent current (12mA vs 5mA). | Designed for mobile CPU VRMs; includes telemetry reporting not needed in industrial power supplies. | Choose ISL95836IRZ only when Intel-compatible digital control and telemetry are required. |
Compared with MP2940AGQ-DC and ISL95836IRZ, the LTC3865EUH#PBF provides superior analog flexibility-supporting both pin-strapped and resistor-programmed outputs, independent soft-start, and three selectable light-load modes-making it optimal for custom industrial and telecom power designs where configurability outweighs integration density.
Availability
LTC3865EUH#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom line cards, and industrial PLC backplanes requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LTC3865EUH#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 the LTC portfolio.
The LTC3865EUH#PBF belongs to Linear's high-performance power controller family, designed specifically for demanding multi-rail, high-efficiency DC/DC conversion in computing, communications, and industrial infrastructure.
FAQ
What is the maximum switching frequency supported by the LTC3865EUH#PBF?
The LTC3865EUH#PBF supports a phase-lockable switching frequency up to 770kHz, set via the FREQ pin using an external resistor. At RFREQ = 0Ω, minimum frequency is 250kHz; at RFREQ ≥ 325kΩ, maximum is 770kHz. This high-frequency capability enables use of small magnetics and ceramic capacitors in space-constrained designs.
Does the LTC3865EUH#PBF support independent enable/disable of each channel?
Yes, the LTC3865EUH#PBF provides independent RUN1 and RUN2 pins (Pins 30 and 11). Pulling either pin below 1.22V disables its respective control loop and gate drivers while leaving the other channel fully operational-enabling dynamic rail shutdown in multi-voltage systems without affecting overall system stability.
How does the ILIM pin affect current sensing on the LTC3865EUH#PBF?
The ILIM pin (Pin 13) configures the maximum current sense threshold for both channels: tied to SGND = 24mV, FLOAT = 50mV, or INTVCC = 75mV (E-grade). This allows optimization for different sensing methods-e.g., 50mV for standard 2mΩ RSENSE, or 24mV for ultra-low-loss DCR networks-without changing external components.
Can the LTC3865EUH#PBF operate with only one output active?
Yes, the LTC3865EUH#PBF supports single-output operation. Disable one channel by grounding its RUN pin while configuring the active channel's VID pins and feedback network. The unused channel's gate drivers remain inactive, and its ITH, TK/SS, and VOSENSE pins can be left unconnected or tied to appropriate bias points per datasheet guidelines.
What is the purpose of the EXTVCC pin on the LTC3865EUH#PBF?
The EXTVCC pin (Pin 20) allows bypassing the internal 5V LDO by connecting a clean, regulated 4.7V–6V supply-typically derived from one of the LTC3865EUH#PBF's own outputs. This improves overall system efficiency by eliminating LDO losses, especially in high-current applications where INTVCC current exceeds 80mA.
LTC3865EUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- 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):
- 4.5V ~ 38V
- Frequency - Switching:
- 250kHz ~ 770kHz
- Duty Cycle (Max):
- 95%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3865EUH#PBF FAQ
1.How can I place an order for LTC3865EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3865EUH#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 LTC3865EUH#PBF reliable?
The price and inventory of LTC3865EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3865EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3865EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3865EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3865EUH#PBF?
LTC3865EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3865EUH#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 LTC3865EUH#PBF?
For technical support, including LTC3865EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3865EUH#PBF requirements.
6.How does Aetrix verify that LTC3865EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3865EUH#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 LTC3865EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3865EUH#PBF?
All LTC3865EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3865EUH#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 LTC3865EUH#PBF part is unused and in its original packaging.
Return procedure for LTC3865EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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