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Analog Devices Inc. LTC3865EFE#TRPBF
- Part No.:
- LTC3865EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3865EFE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,312
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Product details
Overview
LTC3865EFE#TRPBF from Analog Devices (formerly Linear Technology) is a dual, 2-phase synchronous step-down DC/DC controller driving all-N-channel MOSFET stages. It operates with 180° phase separation, supports 4.5V–38V input, delivers up to 95% efficiency, and features pin-selectable output voltages (0.6V–5V) via VID strapping - used in high-density server power distribution and multi-rail FPGA core/memory supplies.
For engineers reviewing the LTC3865EFE#TRPBF datasheet, LTC3865EFE#TRPBF pinout, LTC3865EFE#TRPBF application, or LTC3865EFE#TRPBF equivalent, key selection criteria include its dual-channel current-mode architecture, phase-lockable 250kHz–770kHz switching frequency, OPTI-LOOP® compensation for wide capacitor/ESR tolerance, independent track/soft-start control per channel, and RSENSE/DCR current sensing flexibility.
Technical Context
The LTC3865EFE#TRPBF implements two independent constant-frequency current-mode control loops with 180° phase offset to reduce input/output ripple and EMI. Each channel uses an error amplifier (EA) with transconductance gm = 2.2 mmho and ITH-based peak current programming, where ITH voltage (0.5V–1.6V) directly sets the current comparator threshold.
Its MODE/PLLIN pin enables three operating modes - Burst Mode® (high-efficiency light-load), pulse-skipping, or forced continuous conduction - while FREQ pin sets oscillator frequency via external resistor (7.5μA sink). 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, supporting fast switching (25ns rise/fall) and anti-shoot-through logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide industrial and telecom input rails without pre-regulation. |
| Switching Frequency | 250kHz to 770kHz (phase-lockable) - enables optimization of size vs. efficiency and EMI compliance. |
| Output Voltage Range | 0.6V to 5.0V (via 2-pin VID strapping) - provides precise, programmable dual-rail outputs for CPU/FPGA cores and I/O. |
| Efficiency | Up to 95% - achieved via synchronous N-MOSFET drive, low driver RDS(ON), and optimized gate timing. |
| Current Sensing | RSENSE or DCR - flexible selection accommodates low-loss inductor sensing or high-accuracy shunt-based monitoring. |
| Soft-Start Control | 1.3μA internal charge current on TK/SS pins - enables controlled ramp-up of dual outputs with external capacitor. |
| Thermal Performance | θJA = 25°C/W (TSSOP) - lower junction-to-ambient resistance than QFN variant, improving power density at high load. |
Pinout & Package
Package: 38-Lead Plastic TSSOP (FE package), exposed pad (Pin 39) connected to SGND - requires PCB thermal pad soldering for optimal thermal performance and signal integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 | Independent enable inputs | Each pulls up internally (1μA); >1.22V enables channel; <1.1V disables - allows staggered startup or fault isolation. |
| TK/SS1, TK/SS2 | Tracking/Soft-Start control | Internal 1.3μA current charges external capacitor - sets linear VOUT ramp rate or enables master-slave voltage tracking. |
| VID11, VID12, VID21, VID22 | Output voltage programming | Tie to GND/INTVCC/float to select one of nine preset VOUT values (e.g., 1.2V, 1.5V, 1.8V, 3.3V) - no external DAC needed. |
| MODE/PLLIN | Operating mode & sync input | SGND = forced CCM; INTVCC = pulse-skip; float = Burst Mode®; external clock = PLL sync - single-pin multimode control. |
| PGOOD1, PGOOD2 | Dual open-drain power-good indicators | Assert low when respective VOUT deviates >±10% - enables system-level sequencing and fault reporting without external comparators. |
| TG1, TG2 / BG1, BG2 | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6Ω/1.5Ω (TG), 3Ω/1.4Ω (BG) on-resistance - minimizes switching losses and supports >1MHz operation. |
| SENSE1+, SENSE1− / SENSE2+, SENSE2− | Differential current sense inputs | Accept DCR network or shunt resistor signals - reject common-mode noise and support accurate cycle-by-cycle current limiting. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces input RMS current by ~30% and output voltage ripple amplitude by ~70% versus single-phase design. |
| OPTI-LOOP® compensation | Enables stable loop response across 10× variation in output capacitance and ESR - eliminates re-tuning for different ceramic/tantalum stacks. |
| Adjustable current limit via ILIM pin | Three thresholds (24mV/44mV/68mV for E-grade) set by tying ILIM to GND/float/INTVCC - simplifies overcurrent protection tuning. |
| Output OV protection with reverse current limit | Disables bottom FET before inductor current reverses - prevents shoot-through during light-load transitions and improves transient recovery. |
| Power Good monitoring with 100μs blanking | Internal timer masks false trips during startup/voltage overshoot - ensures reliable system power sequencing without external delay circuits. |
Applications
| Server VRM Power Delivery | FPGA Core & I/O Supply |
|---|---|
Use Scenario: Dual-rail 1.2V/15A and 1.5V/15A supply for high-performance Xilinx UltraScale+ FPGA with strict transient response requirements. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing interleaved switching, current sharing, and coordinated soft-start. Use Value: 180° phasing cuts output ripple by 70%, reducing bulk capacitance by 40%; OPTI-LOOP® maintains stability with mixed MLCC/tantalum output caps. |
Use Scenario: Multi-voltage rail generation for Intel Agilex FPGA requiring tightly tracked 0.85V core, 1.2V GT transceiver, and 3.3V I/O supplies. IC Role / Device Role / Timing Role: Primary controller for core rail; secondary channel configured as slave for tracking via TK/SS2 resistor divider. Use Value: Independent TK/SS pins enable precise voltage ramp alignment (<1% mismatch); VID strapping eliminates need for external DAC or EEPROM. |
| Telecom Line Card Power | Industrial PLC CPU Module |
Use Scenario: 48V-to-12V/5V dual-output converter on carrier-grade line card with limited board area and thermal budget. IC Role / Device Role / Timing Role: High-efficiency dual-phase controller operating in Burst Mode® during standby, switching to CCM under load. Use Value: 95% peak efficiency reduces heat sink size; 250kHz–770kHz frequency range allows EMI filtering at 450kHz fundamental to meet CISPR-32 Class B. |
Use Scenario: Robust 24V-to-3.3V/5V power for ARM Cortex-A9-based PLC CPU with extended temperature (-40°C to 125°C) and surge immunity needs. IC Role / Device Role / Timing Role: Dual-channel controller with RSENSE current sensing and independent RUN pin shutdown for fault containment. Use Value: Wide VIN (4.5V–38V) tolerates 24V brownouts and surges; EXTVCC pin enables self-powered operation from local 5V rail to improve efficiency. |
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 |
|---|---|---|---|
| MP8765GL-10-Z | Single-chip dual-phase controller with integrated 40V/5A MOSFETs; fixed 500kHz frequency; no VID programming. | Targeted at space-constrained consumer/industrial apps; lacks phase-locking, adjustable frequency, and independent soft-start. | Select when board area is critical and discrete MOSFETs are undesirable; avoid if frequency synchronization or multi-rail tracking is required. |
| ISL95836IRZ-T | Intel VR12.5-compliant dual-phase controller; supports SVID interface; 300kHz–1.5MHz range; no TSSOP package option. | Designed for notebook CPU VRMs; requires SVID host communication; higher pin count (40-QFN only). | Choose for SVID-based systems needing dynamic VID updates; not suitable for standalone VID-strapped or non-SVID designs. |
Compared with MP8765GL-10-Z and ISL95836IRZ-T, the LTC3865EFE#TRPBF offers unique flexibility in frequency tuning, phase synchronization, and analog VID configuration - making it preferred for custom industrial, telecom, and FPGA power where discrete MOSFET selection and layout control are essential.
Availability
LTC3865EFE#TRPBF is available at Aetrix Electronics and suitable for server VRM power delivery, FPGA core/I/O supply, and telecom line card power requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to +125°C operation.
Supply support for LTC3865EFE#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 power management portfolio with rigorous automotive- and industrial-grade qualification.
The LTC3865EFE#TRPBF belongs to Linear's precision dual-phase controller product line, engineered for high-efficiency, multi-rail DC/DC conversion in demanding computing, networking, and industrial applications where reliability and thermal robustness are critical.
FAQ
What is the maximum supported switching frequency for the LTC3865EFE#TRPBF?
The LTC3865EFE#TRPBF supports a phase-lockable switching frequency range of 250kHz to 770kHz. At RFREQ = 0Ω, minimum frequency is 250kHz (typical); at RFREQ ≥ 325kΩ, maximum frequency reaches 770kHz (typical). The FREQ pin sinks a precise 7.5μA current, enabling accurate resistor-based frequency setting - critical for EMI compliance and thermal management in the LTC3865EFE#TRPBF design.
Does the LTC3865EFE#TRPBF support independent enable and soft-start for each channel?
Yes, the LTC3865EFE#TRPBF provides fully independent control: RUN1 and RUN2 pins allow per-channel enable/disable with 1.22V threshold and hysteresis, while TK/SS1 and TK/SS2 pins accept separate external capacitors to set individual soft-start ramp rates. This enables staggered startup, fault isolation, and precise voltage tracking - a key capability distinguishing the LTC3865EFE#TRPBF from single-enable dual controllers.
How does the ILIM pin affect current limit programming on the LTC3865EFE#TRPBF?
The ILIM pin on the LTC3865EFE#TRPBF selects the maximum current sense threshold: tied to GND → 24mV (E-grade), float → 44mV, or INTVCC → 68mV. This adjusts the peak inductor current limit without changing external sense resistors - simplifying design iterations and enabling dynamic derating. Note that the LTC3865-1 variant fixes this threshold at 50mV, confirming the LTC3865EFE#TRPBF's configurability advantage.
Can the LTC3865EFE#TRPBF operate with only one channel active?
Yes, the LTC3865EFE#TRPBF supports single-channel operation: pulling RUN2 low disables Channel 2 while Channel 1 remains fully functional with independent regulation, soft-start, and protection. The unused channel's gate drivers (TG2/BG2), sense inputs, and VID pins can be left unconnected - preserving full performance for the active channel, unlike some dual controllers that require matched loading.
What package thermal advantages does the FE (TSSOP) variant offer over the UH (QFN) for the LTC3865EFE#TRPBF?
The LTC3865EFE#TRPBF in 38-lead TSSOP (FE package) has θJA = 25°C/W, significantly lower than the 32-lead QFN (UH) variant's θJA = 34°C/W. This 26% improvement in junction-to-ambient thermal resistance enables higher continuous power delivery in constrained airflow environments - a decisive factor for dense telecom or industrial modules where the LTC3865EFE#TRPBF replaces less thermally efficient alternatives.
LTC3865EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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:
- 38-TSSOP-EP
LTC3865EFE#TRPBF FAQ
1.How can I place an order for LTC3865EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3865EFE#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 LTC3865EFE#TRPBF reliable?
The price and inventory of LTC3865EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3865EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3865EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3865EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3865EFE#TRPBF?
LTC3865EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3865EFE#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 LTC3865EFE#TRPBF?
For technical support, including LTC3865EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3865EFE#TRPBF requirements.
6.How does Aetrix verify that LTC3865EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3865EFE#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 LTC3865EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3865EFE#TRPBF?
All LTC3865EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3865EFE#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 LTC3865EFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3865EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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