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Analog Devices Inc. LTC3865IUH-1#PBF
- Part No.:
- LTC3865IUH-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3865IUH-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,795
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Product details
Overview
LTC3865IUH-1#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 dual-output regulation (e.g., 1.5V/15A and 1.2V/15A), supports phase-locked frequencies up to 770kHz, enables OPTI-LOOP® compensation, and operates across 4.5V–38V input with independent track/soft-start control - used in high-density server VRMs and telecom power distribution.
For engineers reviewing the LTC3865IUH-1#PBF datasheet, LTC3865IUH-1#PBF pinout, LTC3865IUH-1#PBF application, or LTC3865IUH-1#PBF equivalent, key selection criteria include dual 180° phased operation, VID-programmable output voltage (0.6V–5V), RSENSE/DCR current sensing, adjustable current limit via ILIM pin, and support for Burst Mode®, pulse-skipping, or forced continuous conduction modes.
Technical Context
The LTC3865IUH-1#PBF implements a constant-frequency current-mode architecture with two independent control loops operating 180° out-of-phase to minimize input ripple and thermal stress. Each channel features an error amplifier with transconductance of 2.2 mmho, ITH-based peak current control, and programmable overvoltage lockout (±10% trip level on VOSENSE).
It integrates dual N-channel gate drivers (TG/BG) with 2.6Ω pull-up and 1.5Ω pull-down on TG, 3Ω/1.4Ω on BG, 25ns transition times, and synchronous shoot-through protection. The MODE/PLLIN pin selects operating mode or accepts external clock synchronization, while FREQ sets oscillator frequency (250–770kHz) via a 7.5μA current sink.
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. |
| Output Voltage Range | 0.6V to 5.0V - set via VID pins (9 discrete levels) or external resistive dividers; I-grade accuracy ±1.2% over –40°C to 125°C. |
| Switching Frequency | 250kHz to 770kHz - adjustable via FREQ pin resistor; phase-lockable to external clock on MODE/PLLIN. |
| Current Sensing | RSENSE or DCR - supports low-loss inductor-based sensing; max sense threshold configurable (22–84mV) via ILIM pin. |
| Efficiency | Up to 95% - achieved at 15A load with optimized MOSFETs and layout; Burst Mode® extends light-load efficiency. |
| Thermal Range | –40°C to +125°C junction - specified and guaranteed for industrial and extended-temperature applications. |
| Package | 32-pin 5mm × 5mm QFN (UH) - exposed pad soldered to SGND for thermal performance (θJC = 3°C/W). |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND). Requires PCB soldering of exposed pad for thermal and signal integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOSENSE1 / VOSENSE2 (Pins 1, 8) | Error amplifier feedback input | Accepts remote-sensed output voltage or external divider node; enables precision regulation with ESR compensation. |
| 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 voltage sequencing. |
| ITH1 / ITH2 (Pins 3, 6) | Error amplifier output / current threshold | Controls peak inductor current; voltage range 0–2.7V maps to full current limit scale; used for loop compensation. |
| VID11/12/21/22 (Pins 4,5,12,28) | Output voltage programming inputs | Binary-coded selection of 9 preset VOUT levels (0.6V–5.0V); floating/GND/INTVCC logic states define each channel's target. |
| ILIM (Pin 13) | Current sense threshold select | Configures max sense voltage (22/42/66mV for I-grade); default 50mV in LTC3865-1 variant - matches LTC3865IUH-1#PBF. |
| PGOOD1 / PGOOD2 (Pins 14, 27) | Dedicated power-good indicators | Open-drain outputs asserting low when respective VOUT deviates >±10%; includes 100μs blanking after startup. |
| MODE/PLLIN (Pin 27) | Operating mode & sync input | Selects Burst Mode® (float), pulse-skip (INTVCC), or forced CCM (GND); accepts external clock for synchronization. |
| FREQ (Pin 29) | Oscillator frequency set | 7.5μA current sink; resistor to SGND sets fSW from 250kHz (0Ω) to 770kHz (≥325kΩ). |
| TG1/TG2, BG1/BG2 (Pins 25,16,23,19) | N-channel gate drivers | Drives top/bottom MOSFET gates; TG swing = INTVCC + SW node; BG swing = PGND to INTVCC; anti-shoot-through logic included. |
| SW1/SW2 (Pins 26,15) | Switch node connections | Connects to inductor high-side; voltage swings from ~–0.3V (Schottky drop) to VIN; requires low-inductance layout. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces input capacitor RMS current by ~30% and eases thermal management in high-current designs. |
| OPTI-LOOP® compensation | Enables stable loop response across wide range of output capacitance (10μF–1000μF) and ESR (0.5mΩ–50mΩ). |
| Independent track/soft-start | Allows precise power sequencing (e.g., core before I/O) or synchronized ramping of dual supplies using resistor dividers. |
| Output overvoltage protection | Hardware-level OV detection (±10%) disables top FET within microseconds; prevents damage to downstream loads. |
| Adjustable current foldback | Reduces MOSFET conduction loss during short-circuit by lowering peak current limit based on sensed voltage. |
Applications
| Server Voltage Regulator Modules | Telecom Power Distribution |
|---|---|
Use Scenario: Dual-rail CPU/GPU core and I/O supply generation in 1U rack servers with strict space and thermal constraints. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing 1.2V/15A and 1.5V/15A rails with interleaved switching and coordinated soft-start. Use Value: Achieves >94% efficiency at full load and reduces input ripple by 50% vs single-phase, enabling smaller bulk capacitors. | Use Scenario: Distributed 3.3V and 1.8V supplies for FPGA, DSP, and SerDes in 48V intermediate bus telecom systems. IC Role / Device Role / Timing Role: Primary controller for point-of-load conversion; uses VID strapping for factory-set outputs and MODE/PLLIN for system-wide clock sync. Use Value: Supports phase-locking to backplane clock, eliminating beat frequencies and simplifying EMI filtering. |
| Industrial PLC Power Management | High-Performance Test Equipment |
Use Scenario: Isolated dual-output power for analog front-end (±15V derived) and digital logic (3.3V/5V) in programmable logic controllers. IC Role / Device Role / Timing Role: Controller for non-isolated secondary stage; leverages TK/SS pins for controlled power-up sequencing across isolated domains. Use Value: Prevents latch-up or brown-out during cold start via independent soft-start timing and reverse-current limiting. | Use Scenario: Precision dual-rail supply (±12V or 5V/3.3V) for ADC/DAC reference and signal chain biasing in automated test equipment. IC Role / Device Role / Timing Role: High-accuracy buck controller with <±1.2% output tolerance and low-noise OPTI-LOOP® loop response. Use Value: Maintains <0.5% load regulation and <10mV ripple under dynamic 10A step loads, preserving measurement fidelity. |
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 |
|---|---|---|---|
| LTC3865EUH-1#PBF | E-grade (0°C to 85°C), identical pinout, same VID/ILIM behavior, but not guaranteed over full –40°C to 125°C range. | Suitable for commercial-temperature environments only; not qualified for extended industrial or automotive use. | Select when ambient temperature stays above 0°C and cost sensitivity outweighs extended temp qualification. |
| MP2918GL-Z | Monolithic dual-phase controller (integrated MOSFETs), fixed 600kHz fSW, no VID programming, lower max VIN (24V), no PLL sync. | Targets space-constrained, medium-power apps (<20A per rail); lacks flexibility for wide-input or synchronized multi-rail systems. | Choose for simplified BOM and layout where input ≤24V and temperature ≤85°C; avoid if phase sync or 38V input needed. |
Compared with LTC3865EUH-1#PBF, the LTC3865IUH-1#PBF guarantees full –40°C to 125°C operation and tighter output voltage accuracy; versus MP2918GL-Z, it offers higher input voltage, external MOSFET flexibility, VID programmability, and PLL synchronization - critical for scalable, high-reliability power systems.
Availability
LTC3865IUH-1#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom power distribution, industrial PLCs, and high-performance test equipment requiring stable component supply, long-term lifecycle support, and guaranteed extended-temperature performance.
Supply support for LTC3865IUH-1#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 its high-performance power management portfolio with rigorous qualification and long-term support.
The LTC3865 family is designed for high-efficiency, dual-output, multiphase DC/DC conversion in demanding applications including data center infrastructure, communications equipment, and industrial automation - emphasizing precision, thermal robustness, and design flexibility.
FAQ
What is the key difference between LTC3865IUH-1#PBF and LTC3865IUH#PBF?
The LTC3865IUH-1#PBF incorporates the -1 variant feature set: dedicated PGOOD1 and PGOOD2 pins (separate open-drain outputs per channel), whereas the base LTC3865IUH#PBF uses a single co-bonded PGOOD output. Both share identical thermal grade (I-grade, –40°C to 125°C), package, and electrical specifications. The -1 version enables independent power-good monitoring essential for fault-tolerant systems.
Does LTC3865IUH-1#PBF support external synchronization, and how is it implemented?
Yes, LTC3865IUH-1#PBF supports external synchronization via the MODE/PLLIN pin. When an external clock signal (TTL/CMOS compatible) is applied to this pin, the internal oscillator locks to it, forcing continuous conduction mode and aligning switching edges across multiple controllers. This eliminates beat frequencies in multi-rail systems and simplifies EMI filter design - a capability confirmed in the functional diagram and "Operation" section of the datasheet.
How does the ILIM pin affect current limit configuration in LTC3865IUH-1#PBF?
In LTC3865IUH-1#PBF, the ILIM pin (Pin 13) sets the maximum current sense threshold: tying to SGND selects 22mV, floating selects 42mV, and tying to INTVCC selects 66mV (I-grade min/max values). Unlike the base LTC3865, the -1 variant fixes its default threshold at 50mV - a value explicitly stated in Note 8 of the Electrical Characteristics table and validated across temperature.
Can LTC3865IUH-1#PBF operate with only one channel active?
Yes, LTC3865IUH-1#PBF supports independent channel enable/disable via RUN1 and RUN2 pins. Pulling either pin below 1.1V disables its associated control loop, gate drivers, and feedback circuitry while the other channel remains fully operational. This allows flexible power staging - for example, powering auxiliary rails only when needed - without affecting the active channel's regulation or protection features.
What is the purpose of the EXTVCC pin on LTC3865IUH-1#PBF, and what voltage range is safe?
The EXTVCC pin on LTC3865IUH-1#PBF provides an alternative power source for the INTVCC regulator. When driven between 4.7V and 6V, it bypasses the internal LDO and directly powers internal circuitry, improving efficiency and reducing self-heating. Voltages below 4.5V are ignored; exceeding 6V violates Absolute Maximum Ratings and risks permanent damage - confirmed in both Absolute Maximum Ratings and "INTVCC/EXTVCC Power" sections.
LTC3865IUH-1#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)
LTC3865IUH-1#PBF FAQ
1.How can I place an order for LTC3865IUH-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3865IUH-1#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 LTC3865IUH-1#PBF reliable?
The price and inventory of LTC3865IUH-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3865IUH-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3865IUH-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3865IUH-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3865IUH-1#PBF?
LTC3865IUH-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3865IUH-1#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 LTC3865IUH-1#PBF?
For technical support, including LTC3865IUH-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3865IUH-1#PBF requirements.
6.How does Aetrix verify that LTC3865IUH-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3865IUH-1#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 LTC3865IUH-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3865IUH-1#PBF?
All LTC3865IUH-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3865IUH-1#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 LTC3865IUH-1#PBF part is unused and in its original packaging.
Return procedure for LTC3865IUH-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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