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Analog Devices Inc. LTC3865IUH#PBF
- Part No.:
- LTC3865IUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3865IUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,100
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Product details
Overview
LTC3865IUH#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 up to 95% efficiency, supports 4.5V–38V input, operates at phase-lockable frequencies up to 770kHz, and provides independent track/soft-start for each channel - used in high-density server VRMs and telecom power distribution systems.
For engineers reviewing the LTC3865IUH#PBF datasheet, LTC3865IUH#PBF pinout, LTC3865IUH#PBF application, or LTC3865IUH#PBF equivalent, key selection criteria include dual 180°-phased control, VID-programmable output voltages (0.6V–5V), RSENSE/DCR current sensing, adjustable current limit via ILIM pin, and OPTI-LOOP® compensation for wide ESR/capacitance stability.
Technical Context
The LTC3865IUH#PBF implements constant-frequency current-mode control with two independent channels operating 180° out-of-phase to reduce input/output ripple and thermal stress. Each channel features a transconductance error amplifier (gm = 2.2 mmho), programmable current sense threshold (22–84 mV range), and ITH-based peak current control with foldback during short-circuit conditions.
Its MODE/PLLIN pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction - enabling dynamic efficiency optimization across load ranges. The device integrates dual N-channel gate drivers (TG/BG) with 2.6Ω pull-up / 1.5Ω pull-down on TG and 3Ω/1.4Ω on BG, plus internal 5V INTVCC regulator (4.8–5.2V) and EXTVCC switchover at 4.7V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide industrial and telecom input rails without external pre-regulation. |
| Output Voltage Range | 0.6V to 5.0V via VID strapping - enables precise, pin-selectable regulation for multi-rail CPU/GPU core supplies. |
| Switching Frequency | 250kHz to 770kHz (phase-lockable) - allows EMI tuning and optimal inductor sizing for 15A per channel designs. |
| Efficiency | Up to 95% - achieved via low-RDS(on) gate drive, minimized dead-time losses, and optimized current sensing. |
| Current Sensing | RSENSE or DCR - supports both discrete shunt and integrated inductor sensing for layout flexibility and cost optimization. |
| Thermal Grade | –40°C to +125°C junction - qualified for harsh environments including base station power and industrial computing. |
| Package | 32-pin 5mm × 5mm QFN (UH) - exposes SGND pad for low-inductance thermal path and signal integrity. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed SGND pad (Pin 33), thermally enhanced for high-current operation. Pin pitch: 0.5mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOSENSE1, VOSENSE2 (Pins 1, 8) | Error amplifier feedback inputs | Accept remote-sensed output voltage or external resistor divider signals - critical for tight regulation under PCB trace resistance. |
| TK/SS1, TK/SS2 (Pins 2, 7) | Soft-start and tracking control | Internal 1.3μA current charges external capacitor to ramp output voltage linearly - enables controlled power-up sequencing. |
| ITH1, ITH2 (Pins 3, 6) | Error amplifier output / current threshold | Voltage sets peak inductor current per cycle - direct interface for loop compensation and current limiting. |
| VID11/12/21/22 (Pins 4,5,12,28) | Output voltage programming inputs | Binary-coded strapping to GND/INTVCC/float selects one of nine preset VOUT values (0.6V–5.0V) - eliminates external DACs. |
| ILIM (Pin 13) | Current sense threshold select | Tie to SGND/FLOAT/INTVCC to set max sense voltage to 22/50/75 mV - adapts to different RSENSE values without resistor changes. |
| MODE/PLLIN (Pin 27) | Operating mode & sync input | Selects Burst Mode® (float), pulse-skip (INTVCC), or forced CCM (GND); accepts external clock for synchronization - essential for multi-phase noise reduction. |
| FREQ (Pin 29) | Oscillator frequency setting | 7.5μA sink current into external resistor sets fSW - enables precise frequency selection from 250kHz to 770kHz. |
| PGOOD (Pin 14) | Co-bonded power-good indicator | Open-drain output pulled low if either channel deviates >±10% from target - single fault flag for system monitoring logic. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased control | Reduces input RMS current by ~30% and output voltage ripple amplitude by ~70% vs single-phase - lowers bulk capacitor count and size. |
| OPTI-LOOP® compensation | Enables stable loop response across 10× variation in output capacitance and ESR - eliminates re-tuning when changing ceramic/tantalum mix. |
| Independent track/soft-start | Allows master-slave sequencing between 1.5V/15A and 1.2V/15A rails - prevents reverse current flow and ensures safe FPGA/CPU boot order. |
| Current foldback protection | Reduces MOSFET power dissipation during short-circuit by lowering IPEAK as VOUT collapses - maintains thermal safety without external circuitry. |
| DCR or RSENSE sensing | Eliminates power loss and board space of shunt resistors when using inductor DCR - improves light-load efficiency and simplifies thermal design. |
Applications
| Server VRM | Telecom Power Shelf |
|---|---|
Use Scenario: Dual-output 1.5V/15A and 1.2V/15A regulation for high-performance CPU/GPU cores in 1U rack servers. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing gate timing, current sharing, and phase interleaving. Use Value: 180° phasing cuts input capacitor RMS current by 30%, reducing required capacitance and improving reliability under transient loads. | Use Scenario: Distributed 3.3V/20A and 5V/15A DC-DC conversion in modular telecom power shelves with strict EMI limits. IC Role / Device Role / Timing Role: Phase-lockable dual controller synchronized to system clock to suppress switching noise in sensitive RF front-ends. Use Value: PLLIN input enables deterministic frequency alignment across multiple LTC3865IUH#PBF units - eliminates beat frequencies and simplifies EMI filter design. |
| Industrial PLC Power | High-Density FPGA Board |
Use Scenario: Compact 12V-to-1.8V/12A and 12V-to-3.3V/8A conversion in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Dual-channel controller with independent RUN pins enabling isolated enable/disable of I/O and logic rails. Use Value: Independent RUN1/RUN2 pins allow firmware-controlled power sequencing - prevents latch-up during hot-swap or firmware update. | Use Scenario: Multi-rail supply (0.85V core, 1.2V auxiliary, 2.5V I/O) for Xilinx Kintex Ultrascale+ FPGAs in edge AI accelerators. IC Role / Device Role / Timing Role: VID-programmable controller delivering precise voltage setpoints without external DACs or EEPROM configuration. Use Value: 2-pin VID strapping supports nine factory-set outputs - reduces BOM count and eliminates calibration steps in high-volume production. |
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 |
|---|---|---|---|
| MP2965DQ-LF-Z | Single-package dual controller with integrated MOSFET drivers only; no VID pins; fixed 0.6V reference with external resistor programming. | Requires external resistors for VOUT setting; lacks pin-strappable VID flexibility and co-bonded PGOOD. | Choose MP2965DQ-LF-Z for cost-sensitive, lower-current (<10A/channel) applications where VID simplicity is not required. |
| ISL95812IRZ | Supports Intel VR12.5/VR13 protocols; includes SMBus interface; higher quiescent current (12mA vs 3mA normal mode). | Designed specifically for CPU VRMs with telemetry and dynamic VID updates; not suited for generic industrial multi-rail use. | Choose ISL95812IRZ only when Intel-compatible serial VID control and telemetry reporting are mandatory. |
Compared with MP2965DQ-LF-Z and ISL95812IRZ, the LTC3865IUH#PBF uniquely combines pin-strappable VID, co-bonded PGOOD, and true independent channel control - making it optimal for non-Intel, high-reliability, multi-rail industrial and telecom power systems requiring minimal external components and robust sequencing.
Availability
LTC3865IUH#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom power shelves, industrial PLCs, and high-density FPGA boards requiring stable component supply, extended temperature operation (–40°C to +125°C), and long-term lifecycle support.
Supply support for LTC3865IUH#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 continuity, technical documentation, and long-term manufacturing commitment for all Linear power ICs.
The LTC3865IUH#PBF belongs to Linear's high-performance synchronous buck controller family, designed for demanding multi-phase, high-current DC/DC conversion in datacenter, telecom, and industrial infrastructure equipment.
FAQ
What is the maximum supported switching frequency for the LTC3865IUH#PBF?
The LTC3865IUH#PBF supports a phase-lockable switching frequency up to 770kHz, set via an external resistor on the FREQ pin. At RFREQ = 0Ω, minimum frequency is 250kHz; at RFREQ ≥ 325kΩ, maximum is 770kHz. This range enables optimal trade-offs between efficiency, size, and EMI in high-current applications.
Does the LTC3865IUH#PBF support both RSENSE and DCR current sensing?
Yes, the LTC3865IUH#PBF supports both RSENSE and DCR current sensing through dedicated SENSE+ and SENSE– pins per channel. This dual-sensing capability allows designers to choose low-loss DCR sensing for high-efficiency operation or precision RSENSE for better accuracy and transient response - without changing the IC.
How does the ILIM pin affect current limit behavior in the LTC3865IUH#PBF?
The ILIM pin on the LTC3865IUH#PBF selects the maximum current sense threshold: tying ILIM to SGND sets VSENSE(MAX) = 22mV (I-grade), to FLOAT sets 50mV, and to INTVCC sets 75mV. This adjusts the peak inductor current trip point without modifying external sense components - enabling flexible current limit scaling across different MOSFET and inductor combinations.
Can the LTC3865IUH#PBF operate with only one channel enabled?
Yes, the LTC3865IUH#PBF supports independent channel control via RUN1 and RUN2 pins. Pulling RUN1 low disables Channel 1 while leaving Channel 2 fully operational, and vice versa. This enables asymmetric power delivery, staggered startup, or fault isolation - critical in redundant power architectures and mixed-voltage systems.
What is the purpose of the co-bonded PGOOD pin on the LTC3865IUH#PBF?
The co-bonded PGOOD pin (Pin 14) on the LTC3865IUH#PBF is an open-drain output that pulls low if *either* channel's output voltage deviates beyond ±10% of its regulated value. This single-fault indicator simplifies system-level power monitoring and eliminates need for external OR-ing logic - especially valuable in space-constrained server and telecom modules.
LTC3865IUH#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#PBF FAQ
1.How can I place an order for LTC3865IUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3865IUH#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#PBF reliable?
The price and inventory of LTC3865IUH#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#PBF is usually 5 days.
3.What payment methods are accepted for LTC3865IUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3865IUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3865IUH#PBF?
LTC3865IUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3865IUH#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#PBF?
For technical support, including LTC3865IUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3865IUH#PBF requirements.
6.How does Aetrix verify that LTC3865IUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3865IUH#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#PBF meets industry standards.
7.What is the process for return or replacement of LTC3865IUH#PBF?
All LTC3865IUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3865IUH#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#PBF part is unused and in its original packaging.
Return procedure for LTC3865IUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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