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Analog Devices Inc. LTC3866EFE#PBF
- Part No.:
- LTC3866EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3866EFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:124
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Product details
Overview
LTC3866EFE#PBF 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), supports 4.5V–38V input, delivers 0.6V–3.5V output with ±0.5% accuracy, and operates at programmable 250kHz–770kHz frequency. It is used in high-current DC/DC converters for telecom power systems requiring low-noise, high-efficiency regulation.
For engineers reviewing the LTC3866EFE#PBF datasheet, LTC3866EFE#PBF pinout, LTC3866EFE#PBF application, or LTC3866EFE#PBF equivalent, key selection criteria include its differential remote sense amplifier, selectable 10–30 mV current limit threshold, DCR temperature compensation via ITEMP, ±0.5% 0.6 V reference, and support for Burst Mode®, pulse-skipping, and CCM operation across –40°C to 125°C.
Technical Context
The LTC3866EFE#PBF implements a proprietary current-sense architecture that processes dual positive inputs (SNSD+, SNSA+) to improve signal-to-noise ratio by 14 dB-enabling stable control with ultra-low-DCR inductors (≤0.2 mΩ). Its error amplifier regulates VFB against a precise 0.6 V reference, while ITH voltage sets peak inductor current and controls loop dynamics via external RC compensation.
It integrates a high-speed differential amplifier (gain = 0.998–1.002 V/V, GBW = 3 MHz, PSRR = 90 dB) referenced to SGND, with dedicated DIFFP/DIFFN inputs for Kelvin sensing at the load. The controller supports three operating modes-Burst Mode® (for light-load efficiency), pulse-skipping, and continuous conduction-selected via MODE/PLLIN pin state or external clock synchronization.
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 or industrial rails. |
| Output Voltage Accuracy | ±0.5 % at 0.6 V - ensures tight regulation for CPU/GPU core supplies and FPGA I/O rails. |
| Current Sense Threshold | Selectable 10–30 mV in 5 mV steps via ILIM pin - enables precise overcurrent protection with low-DCR inductors. |
| Switching Frequency | 250 kHz to 770 kHz - programmable via FREQ pin current (9–11 µA); allows optimization of size vs. efficiency. |
| Differential Sense Gain | 0.998–1.002 V/V - maintains <0.2 % gain error over temperature for accurate remote voltage regulation. |
| Thermal Shutdown | Die overtemperature protection - disables switching above 125°C junction to prevent damage during overload. |
| Package | 24-lead plastic TSSOP (FE) with exposed pad - θJA = 33°C/W; requires soldered SGND pad for thermal and noise performance. |
Pinout & Package
The LTC3866EFE#PBF is housed in a 24-lead plastic TSSOP (FE) package with an exposed SGND pad (Pin 25) that must be soldered to the PCB ground plane for thermal management and signal integrity. Pin numbering follows standard JEDEC TSSOP top-view convention.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming input | 10 µA current source pulls down; resistor-to-ground sets frequency from 250 kHz to 770 kHz. |
| RUN (Pin 2) | Enable/disable control input | 1.22 V threshold turn-on; internal 1 µA pull-up; hysteresis prevents chatter during power sequencing. |
| TK/SS (Pin 3) | Soft-start or tracking ramp input | 1.25 µA internal charge current enables linear VOUT ramp; supports supply tracking via external divider. |
| ITH (Pin 4) | Error amplifier output / current limit threshold | Voltage sets peak inductor current; also serves as loop compensation node (RC network required). |
| VFB (Pin 5) | Feedback input to error amplifier | Compares remote-sensed output voltage (via DIFFOUT) to 0.6 V reference; high-impedance (<50 nA bias). |
| DIFFOUT (Pin 6) | Differential amplifier output | Drives VFB through resistive divider; provides Kelvin-referenced output voltage signal to EA. |
| DIFFN (Pin 7) | Negative input of diffamp | Must connect near load ground to reject common-mode noise and ensure accurate remote sensing. |
| DIFFP (Pin 8) | Positive input of diffamp | Must connect near load output to capture true load voltage without PCB trace IR drop. |
| SNSD+ (Pin 9) | Primary DCR sense input | Connects to inductor DCR filter with time constant matching L/DCR; main signal path for current sensing. |
| SNS– (Pin 10) | Current comparator negative input | Connected to output ground; forms differential pair with SNSD+/SNSA+ for noise-rejected current measurement. |
| SNSA+ (Pin 11) | Secondary DCR sense input | Filters same DCR signal at 5× bandwidth of SNSD+; combined processing improves SNR by 14 dB. |
| ILIM (Pin 12) | Current limit threshold select | DC voltage sets max sense threshold (10–30 mV); floating or INTVCC disables DCR temp compensation. |
| CLKOUT (Pin 13) | Internal oscillator clock output | 180° out-of-phase with SW node; usable for synchronizing auxiliary converters or monitoring timing. |
| PGND (Pin 14) | Power ground return | Return path for VIN, INTVCC decoupling caps and bottom MOSFET source; separate from SGND for noise isolation. |
| BG (Pin 15) | Bottom gate driver output | Drives N-MOSFET gate between PGND and INTVCC/EXTVCC; RDS(ON) = 1.1 Ω (pull-down), 2.4 Ω (pull-up). |
| SW (Pin 16) | Switch node connection | Connects to inductor, bottom MOSFET drain, and top MOSFET source; swings from ~–0.3 V to VIN. |
| TG (Pin 17) | Top gate driver output | Floating driver referenced to SW; drives top N-MOSFET gate with swing up to VIN + INTVCC. |
| BOOST (Pin 18) | Bootstrap capacitor supply | Connects to (+) terminal of bootstrap cap; swings from ~INTVCC – 0.7 V to VIN + INTVCC. |
| INTVCC (Pin 19) | Internal 5.5 V regulator output | Powers internal logic and drivers; requires 4.7 µF low-ESR cap to PGND; UVLO at 3.4–4.1 V. |
| VIN (Pin 20) | Main input supply | Supplies INTVCC regulator when EXTVCC is inactive; decouple with 0.1–1 µF ceramic cap to PGND. |
| EXTVCC (Pin 21) | External bias supply input | Enables bypass of INTVCC LDO when >4.7 V applied; reduces power loss in high-current applications. |
| ITEMP (Pin 22) | DCR temperature compensation input | Connect to NTC thermistor near inductor; enables automatic current limit adjustment over temperature. |
| PGOOD (Pin 23) | Open-drain power-good indicator | Pulls low when VOUT deviates >±10 % from setpoint after 20 µs debounce; requires external pull-up. |
| MODE/PLLIN (Pin 24) | Mode selection or PLL sync input | SGND = CCM; INTVCC = pulse-skip; float = Burst Mode®; external clock forces sync and CCM. |
| SGND (Pin 25) | Signal ground reference | Exposed pad; must be soldered to PCB ground plane; reference for feedback, compensation, and diffamp. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-path DCR sensing (SNSD+/SNSA+) | 14 dB SNR improvement enables stable control with ≤0.2 mΩ inductor DCR, reducing conduction loss and heat. |
| Programmable current limit (10–30 mV) | Five discrete thresholds via ILIM pin voltage allow precise foldback protection without external components. |
| Differential remote sense amplifier | 0.998–1.002 V/V gain, 3 MHz GBW, and 90 dB PSRR ensure <0.2 % output voltage error under load transients. |
| Three selectable light-load modes | Burst Mode®, pulse-skipping, and CCM-configured via MODE/PLLIN-optimize efficiency across 0.1 A to 30 A loads. |
| Integrated DCR temperature compensation | ITEMP pin accepts NTC thermistor to maintain constant current limit despite inductor DCR drift over temperature. |
| Robust gate drivers | TG/BG drivers deliver 25 ns rise/fall times into 3300 pF; RDS(ON) < 2.6 Ω ensures fast, low-loss MOSFET switching. |
Applications
| Telecom Power Supply | Industrial DC Distribution |
|---|---|
Use Scenario: 12 V input to 1.5 V/30 A point-of-load converter in 48 V telecom shelf with strict efficiency and thermal requirements. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing all-N-channel MOSFETs, DCR-based current sensing, and remote voltage feedback. Use Value: Enables >95 % efficiency at full load using 0.32 mΩ DCR inductor; differential sensing eliminates PCB trace resistance error at the load. | Use Scenario: 24 V industrial bus powering multiple 3.3 V/15 A modules in factory automation PLC backplane. IC Role / Device Role / Timing Role: High-reliability step-down controller with programmable soft-start, output overvoltage protection, and thermal shutdown. Use Value: ±0.5 % output accuracy and 10–30 mV current limit ensure consistent module behavior across temperature and line variation. |
| Medical Imaging Power | High-Performance Computing |
Use Scenario: MRI subsystem requiring low-noise, tightly regulated 0.85 V/20 A supply with minimal EMI and no output voltage droop during imaging pulses. IC Role / Device Role / Timing Role: Current-mode controller with Burst Mode® for standby and CCM for active imaging; uses differential remote sense for stability. Use Value: Dual-path DCR sensing suppresses switching jitter; 20 µs PGOOD debounce prevents false fault triggers during transient loads. | Use Scenario: GPU core rail in AI accelerator card where rapid load steps (0→30 A in <1 µs) demand fast transient response and precise current limiting. IC Role / Device Role / Timing Role: Precision buck controller with 0.6 V ±0.5 % reference, 1.25 µA TK/SS charge current, and 180° CLKOUT for timing alignment. Use Value: Adjustable soft-start prevents inrush; foldback current limit protects MOSFETs during short-circuit events without latch-off. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3866IUF#PBF | Same silicon, QFN-24 (4 mm × 4 mm) package; θJA = 47°C/W vs. FE's 33°C/W; exposed pad is SGND. | Preferred for space-constrained layouts; higher thermal resistance requires more aggressive PCB copper pour. | Select when board area is limited and thermal design accommodates higher junction rise per watt. |
| MP2918GL-Z | Monolithic 30 A buck converter (integrated MOSFETs); fixed 0.6 V reference; no DCR temperature compensation or dual-path sensing. | Used in cost-sensitive, lower-power applications (<20 A); lacks remote sense and precision DCR compensation. | Choose only if integration, BOM count reduction, and simplified layout outweigh need for sub-milliohm DCR support and ±0.5 % accuracy. |
Compared with LTC3866IUF#PBF, the LTC3866EFE#PBF offers lower thermal resistance in TSSOP packaging-critical for sustained 30 A operation-while MP2918GL-Z trades external MOSFET flexibility and DCR sensing fidelity for monolithic simplicity and reduced footprint.
Availability
LTC3866EFE#PBF is available at Aetrix Electronics and suitable for telecom power systems, industrial DC distribution, medical imaging equipment, and high-performance computing applications requiring stable component supply, long-term lifecycle support, and guaranteed −40°C to +125°C operation.
Supply support for LTC3866EFE#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving aerospace, industrial, automotive, and communications 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 precision remote voltage regulation.
FAQ
What is the maximum supported inductor DCR value for stable operation of the LTC3866EFE#PBF?
The LTC3866EFE#PBF is optimized for very low-DCR inductors, supporting stable operation down to 0.2 mΩ with proper PCB layout. While it can function with higher DCR values, its unique dual-path sensing architecture delivers maximum SNR benefit and jitter reduction only below 1 mΩ. For DCR >1 mΩ, conventional single-path controllers may offer comparable performance at lower cost.
Does the LTC3866EFE#PBF support synchronization to an external clock, and how is it configured?
Yes, the LTC3866EFE#PBF supports external clock synchronization via the MODE/PLLIN pin (Pin 24). Applying a clean CMOS/TTL clock signal to this pin forces the internal oscillator into continuous conduction mode and locks its phase to the external source. No additional components are required-just AC-couple the clock and bias MODE/PLLIN to ~1.2 V DC for optimal noise immunity.
How does the DCR temperature compensation work on the LTC3866EFE#PBF, and what component is required?
The LTC3866EFE#PBF implements DCR temperature compensation using the ITEMP pin (Pin 22), which sources 9–11 µA to an external NTC thermistor placed adjacent to the output inductor. As inductor DCR increases with temperature, the NTC resistance decreases, lowering the ITEMP voltage and automatically scaling the current limit threshold to maintain constant peak current. A standard 10 kΩ NTC with β = 3950 K is recommended.
Can the LTC3866EFE#PBF operate with a 5 V input supply, and what is required for proper biasing?
Yes, the LTC3866EFE#PBF supports 4.5 V minimum input and operates reliably at 5 V. For optimal efficiency, tie VIN and INTVCC together when VIN = 5 V-this bypasses the internal LDO and powers the controller directly from the input rail. Ensure EXTVCC remains unconnected or below 4.7 V to avoid conflict; no external regulator is needed.
What is the purpose of the SNSD+ and SNSA+ pins on the LTC3866EFE#PBF, and how should they be filtered?
SNSD+ and SNSA+ are dual positive current sense inputs enabling noise-rejecting DCR measurement. SNSD+ connects to a first-order RC filter matching the inductor's L/DCR time constant (e.g., R1C1 = L/DCR). SNSA+ connects to a second filter with five times higher bandwidth (R2C2 = R1C1/5). This dual-path structure improves SNR by 14 dB, allowing stable control with ≤0.2 mΩ DCR inductors.
LTC3866EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- 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-TSSOP
LTC3866EFE#PBF FAQ
1.How can I place an order for LTC3866EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3866EFE#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 LTC3866EFE#PBF reliable?
The price and inventory of LTC3866EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3866EFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3866EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3866EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3866EFE#PBF?
LTC3866EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3866EFE#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 LTC3866EFE#PBF?
For technical support, including LTC3866EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3866EFE#PBF requirements.
6.How does Aetrix verify that LTC3866EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3866EFE#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 LTC3866EFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3866EFE#PBF?
All LTC3866EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3866EFE#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 LTC3866EFE#PBF part is unused and in its original packaging.
Return procedure for LTC3866EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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