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Analog Devices Inc. LTC3865EUH-1#PBF
- Part No.:
- LTC3865EUH-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3865EUH-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,505
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Product details
Overview
LTC3865EUH-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 1.5V/15A and 1.2V/15A outputs with 180° phase interleaving, 4.5V–38V input range, and pin-selectable VID programming. Used in high-density server VRMs and telecom power distribution systems.
For engineers reviewing the LTC3865EUH-1#PBF datasheet, LTC3865EUH-1#PBF pinout, LTC3865EUH-1#PBF application, or LTC3865EUH-1#PBF equivalent, key selection criteria include dual-channel phase synchronization, independent track/soft-start control, RSENSE or DCR current sensing, OPTI-LOOP® compensation, and selectable Burst Mode®/pulse-skipping/continuous conduction operation.
Technical Context
The LTC3865EUH-1#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 integrated 5V INTVCC regulator. Its phase-lockable oscillator supports 250kHz–770kHz operation via external resistor on FREQ pin.
It uses dual N-channel MOSFET drive architecture with TG/BG drivers (TG RUP = 2.6Ω, BG RDOWN = 1.4Ω), fast transition times (25ns rise/fall), and built-in anti-shoot-through logic. The MODE/PLLIN pin enables mode selection and external clock synchronization, while separate PGOOD1/PGOOD2 open-drain outputs monitor each channel's ±10% regulation window.
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 Programming | 0.6V to 5V via 2-pin VID strapping - enables precise, resistor-free setting of dual outputs for CPU/GPU core and I/O rails. |
| Switching Frequency | 250kHz to 770kHz (phase-lockable) - allows EMI optimization and inductor size reduction while maintaining phase alignment across channels. |
| Current Sensing | RSENSE or DCR - supports low-loss, high-accuracy current monitoring using either discrete sense resistors or inductor DCR networks. |
| Efficiency | Up to 95% - achieved via synchronous N-MOSFET drive, low-driver on-resistance, and optimized gate timing. |
| Thermal Performance | θJA = 34°C/W (QFN) - enables high-power dual-phase operation in compact 5mm × 5mm footprint without forced air. |
| Protection Features | Output OV lockout (±10%), reverse current limiting, current foldback, UVLO (3.3V on INTVCC) - ensures robust fault handling in mission-critical power systems. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed SGND pad (Pin 33), RoHS-compliant, –40°C to 125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOSENSE1 / VOSENSE2 (Pins 1, 8) | Error amplifier feedback inputs | Accept remote-sensed output voltage or external divider signals; enable precision regulation independent of PCB trace IR drop. |
| 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 in multi-rail systems. |
| ITH1 / ITH2 (Pins 3, 6) | Error amplifier output & current threshold | Set peak inductor current via voltage (0–3.3V); directly controls loop gain and transient response through OPTI-LOOP® compensation. |
| VID11/VID12/VID21/VID22 (Pins 4,5,12,28) | Output voltage configuration inputs | Binary-select 9 preset VOUT values per channel (e.g., 1.5V, 1.2V) without external resistors - simplifies BOM and layout. |
| PGOOD1 / PGOOD2 (Pins 14, 13) | Independent power-good indicators | Open-drain outputs pulled low if respective VOUT deviates >±10%; enable safe power sequencing and system-level fault reporting. |
| MODE/PLLIN (Pin 27) | Operating mode select & sync input | Configures Burst Mode®, pulse-skipping, or forced continuous conduction; accepts external clock for deterministic phase alignment. |
| FREQ (Pin 29) | Oscillator frequency set | 7.5μA sink current sets frequency via external resistor (e.g., 162kΩ → 500kHz); enables precise EMI management and thermal balancing. |
| ILIM (Pin 13) | Current sense threshold select | Three-level programming (GND/FLOAT/INTVCC) sets max sense voltage to 30/50/75mV - matches diverse MOSFET RDS(on) or sense resistor values. |
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 filter cost. |
| OPTI-LOOP® compensation | Allows stable loop response across wide range of ceramic capacitor ESR (0.5mΩ–50mΩ) and capacitance (10μF–1000μF), eliminating trial-and-error tuning. |
| Independent track/soft-start | Enables staggered startup of dual outputs (e.g., core before I/O) or synchronized ramping to prevent inrush current stacking in multi-rail systems. |
| Adjustable current limit | Three-level ILIM pin selection avoids overdesigning MOSFETs and sense resistors - optimizes thermal margin and cost for specific load profiles. |
| Output OV protection with reverse current limit | Prevents damage during hot-swap, load dump, or converter fault by clamping VOUT and disabling bottom FET before inductor current reverses. |
Applications
| Server VRM Core Power | Telecom Base Station DC-DC |
|---|---|
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 interleaved switching, current sharing, and precise voltage sequencing. Use Value: Achieves >94% efficiency at full load and <1% output voltage deviation under 10A/μs transient steps - meets Intel VR14 specs. | Use Scenario: Distributed 3.3V/20A and 1.8V/15A supplies powering FPGA, ADC/DAC, and RF front-end modules in macrocell base stations. IC Role / Device Role / Timing Role: Dual-channel controller delivering phase-aligned outputs with independent soft-start to meet 3GPP timing compliance for power-up sequencing. Use Value: 180° phase shift cuts input capacitor RMS current by 50%, reducing thermal stress and extending 105°C electrolytic capacitor lifetime by 2×. |
| Industrial PLC Power Management | High-Density Data Center PSU |
Use Scenario: Compact 24V-to-5V/3.3V dual-rail conversion for programmable logic controllers operating in –40°C to 85°C ambient. IC Role / Device Role / Timing Role: Robust dual-buck controller with wide VIN range, independent RUN pin shutdown, and thermal derating support. Use Value: Built-in UVLO (3.3V on INTVCC), 125°C TJmax rating, and EXTVCC bypass capability ensure reliable start-up and operation during brownouts and high-temperature conditions. | Use Scenario: Secondary-side 12V-to-1.2V/1.8V point-of-load conversion in modular data center PSUs with strict space constraints. IC Role / Device Role / Timing Role: High-frequency (770kHz), small-footprint controller enabling 30% smaller magnetics and reduced board area vs 300kHz alternatives. Use Value: 5mm × 5mm QFN package with exposed thermal pad achieves 34°C/W θJA - sustains 30W total dissipation without heatsink in 6-layer PCB designs. |
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#PBF | Single PGOOD output (co-bonded); ILIM pin functional; default current sense threshold 50mV | Suitable for simpler systems requiring only one power-good signal and fixed current limit | Select when system-level fault reporting uses single PGOOD and current limit is fixed at mid-range. |
| MP2918GL-Z | Integrated MOSFET drivers only (no power stage); 4.5V–28V VIN; no VID pins; single PGOOD | Targeted at cost-sensitive, lower-current (<10A/channel) applications with external MOSFETs | Choose for budget-constrained designs where dual-phase control suffices but VID flexibility and dual PGOOD are unnecessary. |
Compared with LTC3865EUH#PBF and MP2918GL-Z, the LTC3865EUH-1#PBF provides independent PGOOD1/PGOOD2 monitoring and VID-programmable outputs - critical for safety-critical sequencing in multi-rail server and telecom systems where per-rail fault isolation and flexible voltage assignment are mandatory.
Availability
LTC3865EUH-1#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom base station power supplies, and industrial PLC power management requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for LTC3865EUH-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 analog and power management portfolio. Linear pioneered precision DC/DC controllers with features like OPTI-LOOP® and Burst Mode®.
The LTC3865EUH-1#PBF belongs to Linear's high-efficiency dual-phase synchronous buck controller product line, designed specifically for demanding multi-rail power delivery in servers, networking equipment, and industrial automation where phase interleaving, sequencing, and reliability are paramount.
FAQ
What is the key functional difference between LTC3865EUH-1#PBF and LTC3865EUH#PBF?
The LTC3865EUH-1#PBF features separate PGOOD1 and PGOOD2 open-drain outputs for independent monitoring of each channel's regulation status, whereas the LTC3865EUH#PBF uses a single co-bonded PGOOD pin. Additionally, the LTC3865EUH-1#PBF fixes the current sense threshold at 50mV (no ILIM pin function), simplifying design for standard current-sense configurations. This makes LTC3865EUH-1#PBF ideal for systems requiring per-rail fault isolation.
How does the MODE/PLLIN pin configure operating modes on the LTC3865EUH-1#PBF?
The MODE/PLLIN pin on the LTC3865EUH-1#PBF selects three distinct operating modes: tie to SGND for forced continuous conduction, to INTVCC for pulse-skipping mode, or leave floating for Burst Mode® operation. It also accepts an external clock signal to synchronize both channels' switching frequency and phase - essential for EMI reduction in dense PCB layouts. No external components are needed for basic mode selection.
Can the LTC3865EUH-1#PBF support output voltage tracking during startup?
Yes, the LTC3865EUH-1#PBF supports precise output voltage tracking via its TK/SS1 and TK/SS2 pins. When configured as master/slave, a resistor divider from the master's output to SGND applied to the slave's TK/SS pin replicates the master's soft-start ramp. Internal 1.3μA pull-up current enables standalone soft-start with a single capacitor. This ensures controlled, coordinated power-up of multiple rails - critical for FPGAs and ASICs with strict sequencing requirements.
What is the purpose of the ILIM pin on the LTC3865EUH-1#PBF, and how is it used?
The ILIM pin on the LTC3865EUH-1#PBF is not functional; it is reserved and must be left unconnected. Unlike the standard LTC3865, the -1 variant fixes the maximum current sense threshold at 50mV for both channels, eliminating the need for external configuration. This simplifies design for applications using typical 5mΩ–10mΩ sense resistors or standard DCR networks, reducing BOM count and layout complexity.
Does the LTC3865EUH-1#PBF support external synchronization, and what is the required clock specification?
Yes, the LTC3865EUH-1#PBF supports external synchronization via the MODE/PLLIN pin. A clean CMOS or TTL clock signal (1Vpp minimum, 50% duty cycle, 250kHz–770kHz range) applied to this pin forces both channels into continuous conduction and locks their internal oscillator to the external source. This eliminates beat frequencies and enables deterministic EMI filtering in multi-converter systems - a key requirement in 5G infrastructure and high-speed data centers.
LTC3865EUH-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)
LTC3865EUH-1#PBF FAQ
1.How can I place an order for LTC3865EUH-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3865EUH-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 LTC3865EUH-1#PBF reliable?
The price and inventory of LTC3865EUH-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 LTC3865EUH-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3865EUH-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3865EUH-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3865EUH-1#PBF?
LTC3865EUH-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3865EUH-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 LTC3865EUH-1#PBF?
For technical support, including LTC3865EUH-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3865EUH-1#PBF requirements.
6.How does Aetrix verify that LTC3865EUH-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3865EUH-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 LTC3865EUH-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3865EUH-1#PBF?
All LTC3865EUH-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3865EUH-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 LTC3865EUH-1#PBF part is unused and in its original packaging.
Return procedure for LTC3865EUH-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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