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Analog Devices Inc. LTC3866IUF#TRPBF
- Part No.:
- LTC3866IUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3866IUF#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,015
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Product details
Overview
LTC3866IUF#TRPBF from Analog Devices is a single-phase current-mode synchronous step-down switching regulator controller driving all-N-channel MOSFETs. It enables sub-milliohm DCR sensing (down to 0.2 mΩ), delivers up to 95% efficiency at 30 A output, supports 4.5 V–38 V input and 0.6 V–3.5 V output, and features ±0.5% 0.6 V reference accuracy for precision regulation in high-current DC/DC converters used in telecom power systems.
For engineers reviewing the LTC3866IUF#TRPBF datasheet, LTC3866IUF#TRPBF pinout, LTC3866IUF#TRPBF application, or LTC3866IUF#TRPBF equivalent, key selection criteria include its programmable current sense threshold (10–30 mV), DCR temperature compensation via ITEMP, differential remote sensing amplifier (±0.1% gain error), and 24-lead 4 mm × 4 mm QFN package with exposed SGND pad for thermal management.
Technical Context
The LTC3866IUF#TRPBF implements a proprietary dual-input current sense architecture-SNSD+ and SNSA+-to enhance signal-to-noise ratio for ultra-low-DCR inductors, reducing switching jitter and enabling stable operation with 0.2 mΩ DCR. Its error amplifier drives the ITH pin to control peak inductor current, while the differential amplifier (DIFFP/DIFFN → DIFFOUT) provides precise remote voltage sensing referenced to SGND.
It integrates a 5.5 V internal LDO (INTVCC), supports external bias via EXTVCC ≥4.7 V, and offers three light-load modes-Burst Mode®, pulse-skipping, and continuous conduction-selected via MODE/PLLIN. The oscillator frequency is programmable from 250 kHz to 770 kHz using FREQ pin current (9–11 µA), with CLKOUT providing 180° phase-inverted clock output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 38 V - supports wide bus voltages including 5 V, 12 V, 24 V, and 36 V battery inputs without external regulators. |
| Output Voltage Range | 0.6 V to 3.5 V - set via resistive divider from DIFFOUT to VFB, enabling precise low-voltage CPU/GPU core rails. |
| Feedback Reference | 0.6 V ±0.5% - guarantees ≤±3 mV absolute output voltage error across –40°C to 125°C junction temperature. |
| Current Sense Threshold | Programmable 10 mV / 15 mV / 20 mV / 25 mV / 30 mV via ILIM pin - allows accurate overcurrent protection scaling with DCR value and layout parasitics. |
| Oscillator Frequency | 250 kHz to 770 kHz - adjustable via FREQ pin current; higher frequencies reduce inductor size but increase switching losses. |
| DCR Temp Compensation | Enabled via ITEMP pin with NTC thermistor - maintains constant current limit over temperature by compensating inductor DCR drift. |
| Package | 24-lead 4 mm × 4 mm QFN with exposed SGND pad - θJA = 47°C/W, requires PCB thermal vias for >10 W dissipation. |
Pinout & Package
Package: 24-lead (4 mm × 4 mm) plastic QFN with exposed SGND pad (Pin 25), rated for –40°C to 125°C operating junction temperature. Exposed pad must be soldered to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming input | 10 µA current source sets frequency; 0.4 V–2.4 V range yields 250–770 kHz; enables synchronization when driven externally. |
| RUN (Pin 2) | Enable/disable control input | 1.22 V turn-on threshold with 80 mV hysteresis; internal 1 µA pull-up; supports sequencing and fault shutdown. |
| TK/SS (Pin 3) | Soft-start and tracking control | 1.25 µA internal charge current ramps external capacitor; enables output voltage ramping or supply tracking. |
| ITH (Pin 4) | Error amplifier output / current limit threshold | Voltage sets peak inductor current; also used for loop compensation (RC network to SGND). |
| VFB (Pin 5) | Feedback input to error amplifier | Compares remote-sensed output (via DIFFOUT divider) against 0.6 V reference; <–50 nA bias current minimizes divider error. |
| DIFFOUT (Pin 6) | Differential amplifier output | Provides buffered, gain-1 output of DIFFP–DIFFN; connects to VFB divider to close regulation loop with remote sensing. |
| DIFFN (Pin 7) | Negative input of diffamp | Must be routed near load ground to reject common-mode noise; defines remote sense reference point. |
| DIFFP (Pin 8) | Positive input of diffamp | Must be routed near load output node; enables Kelvin sensing of true load voltage independent of PCB IR drop. |
| SNSD+ (Pin 9) | Primary DCR sense positive input | Connects to inductor DCR filter (R1C1 matching L/DCR); main path for current sensing signal with SNR enhancement. |
| SNS– (Pin 10) | Current comparator negative input | Connected to output rail; forms differential pair with SNSD+/SNSA+ to detect inductor current magnitude. |
| SNSA+ (Pin 11) | Secondary DCR sense positive input | Filters same DCR signal with 5× bandwidth (R2C2 = R1C1/5); combined processing improves SNR by 14 dB vs. single-path sensing. |
| ILIM (Pin 12) | Current sense threshold select | DC voltage sets max sense threshold: 0 V = 10 mV, ¼ INTVCC = 15 mV, ½ INTVCC = 20 mV, etc., enabling precise OCP calibration. |
| CLKOUT (Pin 13) | Phase-inverted clock output | 180° out-of-phase with internal oscillator; usable for synchronizing auxiliary circuits or measuring switching timing. |
| PGND (Pin 14) | Power ground return | Low-impedance return for VIN decoupling, INTVCC cap, and bottom MOSFET source; separates power and signal ground paths. |
| BG (Pin 15) | Bottom gate driver output | Drives N-MOSFET gate between PGND and INTVCC/EXTVCC; 1.1 Ω pull-down RDS(ON) ensures fast turn-off. |
| SW (Pin 16) | Switch node connection | Connects to inductor, bottom MOSFET drain, and top MOSFET source; experiences full VIN-to-GND swing with fast edges. |
| TG (Pin 17) | Top gate driver output | Floating driver referenced to SW node; swings from SW + ~5.5 V to SW; requires bootstrap capacitor (CB) on BOOST pin. |
| BOOST (Pin 18) | Bootstrap capacitor connection | Connects (+) terminal of CB; recharges during BG-on phase; dropout detector forces periodic TG off to maintain CB charge. |
| INTVCC (Pin 19) | Internal 5.5 V regulator output | Powers drivers and logic; 5.25–5.75 V regulated; requires 4.7 µF low-ESR capacitor to PGND for stability. |
| VIN (Pin 20) | Main input supply | Supplies INTVCC LDO when EXTVCC is inactive; decouple with 0.1–1 µF ceramic cap close to PGND. |
| EXTVCC (Pin 21) | External bias input | ≥4.7 V bypasses INTVCC LDO; reduces power loss in high-input-voltage applications; must be < VIN and <6 V. |
| ITEMP (Pin 22) | DCR temperature compensation input | Connects to NTC thermistor near inductor; 9–11 µA current generates voltage proportional to temp; disables if floated or tied to INTVCC. |
| PGOOD (Pin 23) | Open-drain power-good indicator | Pulls low when VOUT deviates >±10% from setpoint after 20 µs debounce; requires external pull-up for logic-level signaling. |
| MODE/PLLIN (Pin 24) | Operating mode or sync input | SGND = CCM; INTVCC = pulse-skip; float = Burst Mode®; external clock forces CCM + sync; no internal pull-up/down. |
| SGND (Pin 25) | Signal ground reference | Exposed pad; must be soldered to PCB ground plane; serves as reference for DIFFAMP, EA, compensation, and feedback resistors. |
Key Features
| Feature | Design Value |
|---|---|
| Sub-milliohm DCR sensing | Supports inductors with DCR as low as 0.2 mΩ using dual-path SNSD+/SNSA+ architecture, improving efficiency and reducing thermal stress in >20 A designs. |
| Differential remote sensing | DIFFP/DIFFN inputs with 0.998–1.002 V/V gain and 2 mV offset enable <±10 mV load regulation error at point-of-load, critical for CPU/GPU VRMs. |
| Programmable current limit | Five-step ILIM-selectable thresholds (10–30 mV) allow precise overcurrent protection tuning without changing sense resistor or layout. |
| DCR temperature compensation | ITEMP pin interface with NTC thermistor actively adjusts current limit to counteract inductor DCR drift over –40°C to 125°C. |
| Multi-mode light-load operation | Burst Mode®, pulse-skipping, and CCM selectable via MODE/PLLIN; achieves >85% efficiency at 1% load without audible noise or output ripple issues. |
| Robust gate drive | TG/BG drivers with 1.1–2.6 Ω RDS(ON), 25 ns rise/fall times, and anti-shoot-through logic ensure reliable 30 A+ switching with minimal dead-time loss. |
Applications
| Telecom Base Station Power | Industrial PLC CPU Core Supply |
|---|---|
|
Use Scenario: 12 V input to 1.2 V/30 A output for FPGA or ASIC in 48 V telecom rectifier systems with strict efficiency and thermal requirements. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current DCR-based current sensing and remote voltage feedback. Use Value: Enables >94% efficiency at full load using 0.32 mΩ DCR inductor, eliminating sense resistor losses and reducing board area by 35% vs. shunt-based solutions. |
Use Scenario: 24 V industrial bus converted to 0.85 V/25 A for real-time control processor under variable ambient temperature (–40°C to 85°C). IC Role / Device Role / Timing Role: Precision voltage regulator with DCR temperature compensation and ±0.5% reference ensuring stable core voltage across temperature extremes. Use Value: Maintains ±15 mV output tolerance over temperature via ITEMP-driven current limit adjustment, preventing processor throttling or reset events. |
| Medical Imaging Power Module | Data Center GPU VRM |
|
Use Scenario: Low-noise 5 V to 1.8 V/20 A conversion for CCD sensor array in portable ultrasound equipment requiring EMI compliance. IC Role / Device Role / Timing Role: Burst Mode®-enabled controller delivering ultra-low standby power (<50 µA) while maintaining fast transient response during imaging bursts. Use Value: Achieves <15 mV undershoot on 10 A step load with 2 µs recovery, meeting medical-grade transient immunity standards without added output capacitance. |
Use Scenario: High-density 48 V to 0.75 V/40 A GPU rail in AI accelerator card with tight space constraints and forced-air cooling. IC Role / Device Role / Timing Role: Dual-path DCR sensing controller supporting paralleled phases and differential remote sensing for multi-point voltage monitoring. Use Value: Reduces total sense loss by 75% vs. discrete shunt, lowering thermal design power (TDP) by 2.1 W per phase and enabling 20% higher power density. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2918GL-Z | Fixed 600 kHz frequency; no DCR temperature compensation; only single-path current sensing; 0.6 V ±1% reference. | Lacks ITEMP-driven thermal compensation and dual-path SNR enhancement; suitable for cost-sensitive, moderate-temp applications only. | Select MP2918GL-Z only if DCR drift over temperature is negligible and SNR margin is sufficient for target inductor DCR ≥0.5 mΩ. |
| ISL81601FRZ-T7A | Supports 40 V max input; includes PMBus interface; 0.6 V ±0.5% reference; no dedicated DCR temp compensation pin. | Offers digital telemetry and fault logging but requires external circuitry for DCR thermal compensation; larger 32-QFN package. | Choose ISL81601FRZ-T7A when system-level monitoring, programmability, or higher input voltage margin (>38 V) outweighs analog simplicity and thermal compensation integration. |
Compared with MP2918GL-Z and ISL81601FRZ-T7A, the LTC3866IUF#TRPBF uniquely integrates hardware-based DCR temperature compensation and dual-path sensing for sub-milliohm operation-critical for high-reliability, thermally constrained 30 A+ designs where reference accuracy and current limit stability over temperature are non-negotiable.
Availability
LTC3866IUF#TRPBF is available at Aetrix Electronics and suitable for telecom power systems, industrial PLC CPU supplies, medical imaging modules, and data center GPU VRMs requiring stable component supply, long-term lifecycle support, and guaranteed –40°C to 125°C operation.
Supply support for LTC3866IUF#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving precision instrumentation, communications, and industrial markets.
The LTC3866 belongs to Linear's high-efficiency synchronous controller product line, designed specifically for high-current, low-voltage DC/DC conversion with ultra-low-DCR sensing and robust thermal performance in demanding infrastructure applications.
FAQ
What is the minimum DCR value supported by the LTC3866IUF#TRPBF?
The LTC3866IUF#TRPBF supports inductor DCR values as low as 0.2 mΩ with careful PCB layout, enabled by its dual-path SNSD+/SNSA+ current sensing architecture that improves signal-to-noise ratio by 14 dB. This capability eliminates the need for power-wasting shunt resistors in high-current applications.
How does the LTC3866IUF#TRPBF implement DCR temperature compensation?
The LTC3866IUF#TRPBF uses the ITEMP pin to accept current from an NTC thermistor placed near the output inductor. A 9–11 µA current generates a voltage proportional to temperature, which dynamically adjusts the current sense threshold to maintain constant output current limit across –40°C to 125°C.
Can the LTC3866IUF#TRPBF operate with an external 5 V supply instead of the internal INTVCC regulator?
Yes - the LTC3866IUF#TRPBF supports external bias via the EXTVCC pin. When a voltage ≥4.7 V is applied to EXTVCC, the internal 5.5 V LDO is disabled and EXTVCC directly powers INTVCC, reducing power loss and heat generation in high-input-voltage applications such as 24 V or 36 V systems.
What are the three light-load operating modes of the LTC3866IUF#TRPBF and how are they selected?
The LTC3866IUF#TRPBF offers Burst Mode®, pulse-skipping, and continuous conduction mode (CCM), selected via the MODE/PLLIN pin: grounded for CCM, tied to INTVCC for pulse-skipping, and left floating for Burst Mode®. Each mode optimizes efficiency vs. noise vs. transient response for specific load profiles.
Does the LTC3866IUF#TRPBF require a separate sense resistor for current monitoring?
No - the LTC3866IUF#TRPBF is designed for DCR-based current sensing only. It does not support external sense resistors. Its architecture relies on the inductor's inherent DCR, using SNSD+ and SNSA+ inputs with matched RC filters to extract the current signal while rejecting noise and thermal drift.
LTC3866IUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 250kHz ~ 770kHz
- Duty Cycle (Max):
- -
- 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:
- 24-QFN (4x4)
LTC3866IUF#TRPBF FAQ
1.How can I place an order for LTC3866IUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3866IUF#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 LTC3866IUF#TRPBF reliable?
The price and inventory of LTC3866IUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3866IUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3866IUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3866IUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3866IUF#TRPBF?
LTC3866IUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3866IUF#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 LTC3866IUF#TRPBF?
For technical support, including LTC3866IUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3866IUF#TRPBF requirements.
6.How does Aetrix verify that LTC3866IUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3866IUF#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 LTC3866IUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3866IUF#TRPBF?
All LTC3866IUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3866IUF#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 LTC3866IUF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3866IUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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