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Analog Devices Inc. LTC3866IFE#PBF
- Part No.:
- LTC3866IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3866IFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,322
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Product details
Overview
LTC3866IFE#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 4.5 V to 38 V input, delivers 0.6 V to 3.5 V output with ±0.5% accuracy, and operates at 250 kHz–770 kHz. It is used in high-current DC/DC converters for telecom power systems requiring precise current limiting and thermal compensation.
For engineers reviewing the LTC3866IFE#PBF datasheet, LTC3866IFE#PBF pinout, LTC3866IFE#PBF application, or LTC3866IFE#PBF equivalent, key selection criteria include its differential remote sense amplifier, programmable 10–30 mV current limit threshold, DCR temperature compensation via ITEMP, and FE-package thermal performance (θJA = 33°C/W).
Technical Context
The LTC3866IFE#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 operation with ultra-low-DCR inductors. Its error amplifier regulates VFB against a 0.6 V reference, while ITH voltage sets peak inductor current in current-mode control.
It integrates a high-speed differential amplifier (gain = 0.998–1.002 V/V, GBW = 3 MHz), programmable oscillator (250–770 kHz), and mode-select logic supporting Burst Mode®, pulse-skipping, or continuous conduction via MODE/PLLIN. Thermal shutdown and output overvoltage protection are built-in.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 38 V - supports wide bus voltages including 12 V, 24 V, and 36 V industrial/telecom rails. |
| Output Voltage Accuracy | ±0.5% at 0.6 V reference - ensures tight regulation across load/temperature for CPU/GPU core supplies. |
| Current Sense Threshold | Programmable 10 mV to 30 mV in 5 mV steps via ILIM pin - enables precise foldback current limiting without external resistors. |
| Switching Frequency | 250 kHz to 770 kHz - adjustable via FREQ pin current (9–11 µA) for EMI optimization and inductor size trade-offs. |
| DCR Temp Compensation | Enabled via ITEMP pin with NTC thermistor - maintains accurate current limit over –40°C to 125°C junction range. |
| Differential Sense Gain | 0.998–1.002 V/V with 2 mV offset - rejects common-mode noise for stable remote sensing across PCB traces. |
| Thermal Resistance | θJA = 33°C/W (FE package) - requires minimal copper area for 30 A applications at ≤125°C ambient. |
Pinout & Package
Package: 24-lead plastic TSSOP (FE) with exposed pad (Pin 25 = SGND); RoHS-compliant, lead-free finish; operating junction temperature range –40°C to 125°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming input | 10 µA current source sets frequency from 250 kHz to 770 kHz; voltage-driven alternative available. |
| RUN (Pin 2) | Enable/disable control input | 1.22 V turn-on threshold with 80 mV hysteresis; internal 1 µA pull-up enables controlled startup. |
| TK/SS (Pin 3) | Soft-start and tracking control | 1.25 µA internal charge current ramps external capacitor for monotonic VOUT rise or supply tracking. |
| ITH (Pin 4) | Error amplifier output / current limit threshold | Voltage sets peak inductor current; also used for loop compensation with RC network. |
| VFB (Pin 5) | Feedback input to error amplifier | Compares remote-sensed output voltage (via DIFFOUT divider) to 0.6 V reference for regulation. |
| DIFFOUT (Pin 6) | Differential amplifier output | Drives VFB through resistor divider; provides gain-stabilized, low-offset remote sense signal. |
| DIFFN (Pin 7) | Negative diffamp input | Connected to load ground plane near output capacitor - critical for common-mode rejection. |
| DIFFP (Pin 8) | Positive diffamp input | Connected directly to output rail near load - forms Kelvin sense path with DIFFN. |
| SNSD+ (Pin 9) | Primary DCR sense input | Filters inductor DCR signal with time constant matching L/DCR; main current sensing path. |
| SNS– (Pin 10) | Current comparator negative input | Connected to output node; completes current sense loop with SNSD+/SNSA+ for accurate peak detection. |
| SNSA+ (Pin 11) | Secondary DCR sense input | Filters same DCR signal at 5× bandwidth of SNSD+ - enhances SNR for sub-mΩ sensing. |
| ILIM (Pin 12) | Current limit threshold programming | DC voltage selects max sense threshold (10–30 mV); enables precise foldback without calibration. |
| CLKOUT (Pin 13) | Internal clock output | 180° out-of-phase with SW node; useful for synchronization or timing diagnostics. |
| PGND (Pin 14) | Power ground return | Low-impedance connection point for VIN/INTVCC decoupling caps and bottom FET source. |
| BG (Pin 15) | Bottom gate driver output | Swings between PGND and INTVCC/EXTVCC; drives N-channel MOSFET gate with 1.1 Ω RDOWN. |
| SW (Pin 16) | Switch node connection | Connects to inductor, bottom FET drain, and top FET source; handles full VIN-to-GND voltage swing. |
| TG (Pin 17) | Top gate driver output | Floating driver referenced to SW; swings from SW to SW + INTVCC; drives top N-FET with 2.6 Ω RUP. |
| BOOST (Pin 18) | Bootstrap capacitor supply | Charged during BG on-time; supplies TG driver; must be ≥0.1 µF ceramic near TG/BOOST/SW. |
| INTVCC (Pin 19) | Internal 5.5 V regulator output | Powers internal circuitry; requires 4.7 µF low-ESR cap to PGND; bypassed by EXTVCC > 4.7 V. |
| VIN (Pin 20) | Main input supply | 4.5–38 V input; powers INTVCC regulator when EXTVCC is inactive; decouple with 0.1–1 µF ceramic. |
| EXTVCC (Pin 21) | External bias supply input | Enables high-efficiency biasing from external 4.7–6 V source; disables internal LDO when active. |
| ITEMP (Pin 22) | DCR temperature compensation input | Accepts NTC thermistor voltage to scale current limit vs. inductor temperature; floating = disable. |
| PGOOD (Pin 23) | Open-drain power-good indicator | Pulls low when VOUT deviates >±10% from setpoint after 20 µs mask timer; requires pull-up resistor. |
| MODE/PLLIN (Pin 24) | Operation mode or sync input | SGND = CCM; INTVCC = pulse-skip; float = Burst Mode®; external clock = PLL sync. |
| SGND (Pin 25) | Signal ground reference | Exposed pad; must be soldered to PCB ground plane; reference for compensation, feedback, and diffamp. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-path DCR sensing (SNSD+/SNSA+) | 14 dB SNR improvement enables stable 0.2 mΩ inductor sensing - reduces conduction loss and eliminates need for sense resistors. |
| Programmable current limit (10–30 mV) | Five discrete thresholds via ILIM pin voltage - allows precise foldback protection without trimming or calibration. |
| Differential remote sense amplifier | 0.998–1.002 V/V gain, 2 mV offset, 90 dB PSRR - rejects PCB layout noise and ensures <±0.5% output regulation under load transients. |
| DCR temperature compensation | ITEMP pin accepts NTC voltage to scale current limit with inductor DCR drift - maintains consistent OCP across –40°C to 125°C. |
| Three light-load modes | Burst Mode®, pulse-skipping, and CCM selectable via MODE/PLLIN - optimizes efficiency from 1 mA to 30 A without external components. |
| Integrated gate drivers | TG RUP/RDOWN = 2.6 Ω/1.5 Ω; BG RUP/RDOWN = 2.4 Ω/1.1 Ω - drives 30 A MOSFETs directly with fast 25 ns transitions and anti-shoot-through logic. |
Applications
| Telecom Power Supply | Industrial DC Distribution |
|---|---|
Use Scenario: 12 V input to 1.5 V/30 A core supply for baseband processors in 4G/5G radio units. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current, low-voltage conversion with remote Kelvin sensing. Use Value: Sub-milliohm DCR sensing eliminates power loss from shunt resistors; ±0.5% VOUT accuracy ensures processor stability under dynamic load. | Use Scenario: 24 V bus to 3.3 V/20 A supply for PLC I/O modules in factory automation cabinets. IC Role / Device Role / Timing Role: High-efficiency step-down controller with programmable current limit for overload protection in harsh environments. Use Value: DCR temperature compensation maintains consistent current limit as ambient rises; FE package supports convection cooling without heatsink. |
| Medical Imaging Power | High-Performance Computing |
Use Scenario: 48 V input to 0.85 V/40 A GPU supply in portable ultrasound imaging systems. IC Role / Device Role / Timing Role: Precision current-mode controller with soft-start tracking for multi-rail sequencing. Use Value: TK/SS pin enables output voltage ramp synchronized to auxiliary rails; differential sensing rejects EMI from adjacent analog circuits. | Use Scenario: 12 V input to 1.0 V/50 A FPGA core supply in edge AI inference accelerators. IC Role / Device Role / Timing Role: High-frequency (770 kHz) synchronous controller minimizing inductor size while maintaining 95% peak efficiency. Use Value: Programmable 250–770 kHz switching allows EMI spread-spectrum tuning; integrated drivers reduce gate-drive BOM count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3866EFE#PBF | Same silicon, rated for 0°C to 85°C junction temperature (vs. –40°C to 125°C for LTC3866IFE#PBF) | Not suitable for extended-temperature industrial or automotive under-hood use | Select LTC3866IFE#PBF for designs requiring full –40°C to 125°C operation with guaranteed specs. |
| MP2918GL-Z | Monolithic 30 V buck controller with integrated MOSFETs; no DCR sensing; fixed 600 kHz frequency | Lacks differential remote sense, DCR temp compensation, and sub-mΩ capability | Choose MP2918GL-Z only for cost-sensitive, lower-current (<15 A), non-precision applications where board space is constrained. |
Compared with LTC3866EFE#PBF, the LTC3866IFE#PBF guarantees full –40°C to 125°C performance and tighter thermal shutdown margins; versus MP2918GL-Z, it offers superior precision, flexibility in current sensing, and higher current scalability - essential for mission-critical power delivery.
Availability
LTC3866IFE#PBF is available at Aetrix Electronics and suitable for telecom power systems, industrial DC distribution, medical imaging equipment, and high-performance computing platforms requiring stable component supply across extended temperature ranges.
Supply support for LTC3866IFE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3866IFE#PBF belongs to the Linear Technology (now part of Analog Devices) high-efficiency synchronous controller product line, designed specifically for high-current, low-voltage DC/DC conversion with precision current sensing and thermal robustness.
FAQ
What is the maximum supported inductor DCR value for stable operation of the LTC3866IFE#PBF?
The LTC3866IFE#PBF is optimized for very low DCR inductors down to 0.2 mΩ. While not a hard upper limit, stable operation is confirmed with DCR values ≤1 mΩ using proper PCB layout and matched filter networks on SNSD+ and SNSA+. Higher DCR values degrade SNR benefit and may require conventional shunt-based sensing instead.
Can the LTC3866IFE#PBF operate without an external bootstrap diode?
No - the LTC3866IFE#PBF requires an external Schottky bootstrap diode (e.g., 1N5817) between INTVCC and BOOST to recharge the bootstrap capacitor during BG conduction. Omitting it prevents TG from achieving full gate drive, causing shoot-through or failure to regulate.
How does the LTC3866IFE#PBF handle prebiased output conditions during startup?
The LTC3866IFE#PBF disables the bottom MOSFET until the internal soft-start ramp or TK/SS voltage exceeds VFB, preventing reverse current flow into a precharged output. This avoids uncontrolled discharge and ensures monotonic startup even with residual output capacitance voltage.
What is the purpose of the two current sense inputs (SNSD+ and SNSA+) on the LTC3866IFE#PBF?
SNSD+ and SNSA+ form a dual-path sensing architecture: SNSD+ captures the primary DCR voltage with a filter matching L/DCR, while SNSA+ captures the same signal with 5× higher bandwidth. Their internal combination improves SNR by 14 dB - enabling reliable sub-milliohm sensing without added noise susceptibility.
Is the LTC3866IFE#PBF pin-compatible with other members of the LTC3866 family?
Yes - all LTC3866 variants (LTC3866EFE#PBF, LTC3866IFE#PBF, LTC3866EUF#PBF, LTC3866IUF#PBF) share identical pinouts and footprint. The LTC3866IFE#PBF differs only in temperature grade (–40°C to 125°C) and screening; no PCB redesign is needed when upgrading from E-grade to I-grade.
LTC3866IFE#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
LTC3866IFE#PBF FAQ
1.How can I place an order for LTC3866IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3866IFE#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 LTC3866IFE#PBF reliable?
The price and inventory of LTC3866IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3866IFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3866IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3866IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3866IFE#PBF?
LTC3866IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3866IFE#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 LTC3866IFE#PBF?
For technical support, including LTC3866IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3866IFE#PBF requirements.
6.How does Aetrix verify that LTC3866IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3866IFE#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 LTC3866IFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3866IFE#PBF?
All LTC3866IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3866IFE#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 LTC3866IFE#PBF part is unused and in its original packaging.
Return procedure for LTC3866IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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