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Analog Devices Inc. LTC3891EFE#PBF
- Part No.:
- LTC3891EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3891EFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,729
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Product details
Overview
LTC3891EFE#PBF from Analog Devices (formerly Linear Technology) is a high-performance, low-quiescent-current synchronous step-down DC/DC controller driving all-N-channel MOSFETs. It operates from 4V to 60V input, delivers 0.8V–24V output, supports phase-lockable frequencies up to 750kHz, and features 50μA no-load IQ - enabling long battery runtime in automotive always-on systems and industrial power supplies.
For engineers reviewing the LTC3891EFE#PBF datasheet, LTC3891EFE#PBF pinout, LTC3891EFE#PBF application, or LTC3891EFE#PBF equivalent, key selection criteria include its wide VIN range, selectable light-load modes (Burst/Pulse-Skipping/Forced CCM), OPTI-LOOP® compensation, precision 0.8V reference, and integrated power-good indicator with ±10% trip threshold.
Technical Context
The LTC3891EFE#PBF implements a constant-frequency current-mode control architecture with an internal transconductance error amplifier (gm = 2 mmho) and programmable oscillator (50–900 kHz). Its dual-gate drivers deliver 2.5Ω TG pull-up and 1.1Ω BG pull-down on-resistance, supporting fast switching transitions (TG tr/tf ≤ 25/16 ns) and 99% maximum duty cycle for ultra-low dropout operation.
It integrates dual LDOs: one powered from VIN (4.85–5.35V INTVCC) and another switchover-enabled from EXTVCC (4.5–4.9V threshold), allowing efficient biasing from auxiliary rails. The device uses differential RSENSE or DCR current sensing with three selectable current-limit thresholds (22/43/64 mV) via ILIM pin configuration and includes foldback protection without startup interference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports 12V/24V/48V intermediate buses and Li-ion, lead-acid, and supercapacitor battery chemistries. |
| Quiescent Current (No Load) | 50μA - extends battery life in always-on automotive and portable systems without compromising start-up capability. |
| Output Voltage Range | 0.8V to 24V - programmable via external resistor divider; regulated by precision 0.800V ±1.2mV reference (–40°C to 125°C). |
| Switching Frequency | 50kHz to 900kHz - adjustable via FREQ pin resistor or external clock (75–750kHz PLL-sync); enables optimization of size vs. efficiency. |
| Current Sense Threshold | 22/43/64 mV - selectable via ILIM pin (GND/FLOAT/INTVCC); sets peak current limit without requiring sense resistor recalibration. |
| Power-Good Accuracy | ±10% VFB trip level with 2.5% hysteresis - provides reliable system-level power sequencing and fault detection. |
| Shutdown IQ | <14μA - ensures minimal standby drain when RUN pin is pulled below 0.7V, critical for energy-sensitive applications. |
Pinout & Package
Package: 20-lead plastic TSSOP (FE package), 3mm × 4mm footprint, exposed pad (Pin 21) soldered to SGND for thermal performance (θJA = 38°C/W). RoHS-compliant, lead-free finish (PBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TRACK/SS (Pin 1) | Soft-start & tracking control input | Internal 10µA pull-up charges external capacitor for linear VOUT ramp; accepts external voltage divider to synchronize start-up with other rails. |
| FREQ (Pin 2) | Oscillator frequency programming | 20µA internal pull-up develops voltage across external resistor to set VCO frequency from 50kHz to 900kHz. |
| PLLIN/MODE (Pin 3) | Light-load mode & sync select | Ground = Burst Mode; INTVCC = Forced CCM; 1.2V–(INTVCC–1.3V) = Pulse-Skipping; external clock = PLL-synchronized operation. |
| RUN (Pin 6) | Enable/shutdown control | 1.16V threshold disables regulation; 0.7V threshold shuts down INTVCC LDO and reduces IQ to <14µA - ideal for UVLO implementation. |
| SENSE+ / SENSE– (Pins 7/8) | Differential current sense inputs | Accept RSENSE or DCR network; common-mode range up to 28V; bias current ±1µA minimizes measurement error. |
| VFB (Pin 9) | Feedback voltage input | Compares output divider voltage to 0.800V reference; ±5nA input current enables high-impedance resistive dividers. |
| ITH (Pin 10) | Error amplifier output & compensation node | Controls peak inductor current; connects to external RC network for OPTI-LOOP® compensation across wide ESR/capacitance ranges. |
| PGOOD (Pin 11) | Open-drain power-good indicator | Pulls low when VFB deviates >±10% from target; 2mA sink capability drives logic or microcontroller interrupt directly. |
| TG (Pin 12) | Top N-MOSFET gate driver | Floating driver with 2.5Ω pull-up; swing = INTVCC + SW voltage; supports bootstrap capacitor recharging in dropout. |
| SW (Pin 13) | Switch node connection | Connects to inductor and bootstrap capacitor; withstands –5V to 65V; requires low-inductance layout for EMI control. |
| BOOST (Pin 14) | Bootstrap supply for TG driver | Capacitor between BOOST and SW provides floating bias; Schottky diode from BOOST to INTVCC prevents reverse discharge. |
| BG (Pin 15) | Bottom N-MOSFET gate driver | Ground-referenced driver with 1.1Ω pull-down; complements TG for synchronous rectification and high efficiency. |
| INTVCC (Pin 16) | Internal LDO output (5.1V) | Supplies gate drivers and control circuitry; requires ≥2.2µF ceramic decoupling to PGND; bypassed by EXTVCC above 4.7V. |
| EXTVCC (Pin 17) | External bias input for INTVCC LDO | Enables higher-efficiency biasing from secondary rail (e.g., converter output); switchover hysteresis = 250mV. |
| PGND (Pin 18) | Power ground return | Connects to source of bottom MOSFET and negative terminal of input capacitor; must be separate from SGND plane. |
| VIN (Pin 19) | Main input supply | 4V–60V operating range; requires local ceramic bypass (≥1µF) to SGND pins; absolute max = 65V. |
| ILIM (Pin 20) | Current limit threshold select | GND = 22mV; FLOAT = 43mV; INTVCC = 64mV - configures overcurrent protection level without changing sense resistor. |
| SGND (Pins 4,5,21) | Small-signal ground | Must be routed separately from PGND; Pins 4/5 and exposed pad (21) all connect to same low-noise SGND net. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop response across wide output capacitance (10µF–1000µF) and ESR (0.5mΩ–100mΩ) without redesigning compensation network. |
| Selectably Optimized Light-Load Efficiency | Burst Mode (50μA IQ), Pulse-Skipping, or Forced CCM - lets designers trade off ripple/noise vs. efficiency based on system requirements. |
| Integrated Dual-LDO Bias Architecture | VIN-powered and EXTVCC-powered LDOs enable flexible, high-efficiency gate drive sourcing - critical for multi-rail systems. |
| Three-Level Programmable Current Limit | Hardware-selectable thresholds (22/43/64 mV) simplify design-in across varying load profiles without PCB changes. |
| Dropout Recovery with Bootstrap Recharge | Dropout detector forces periodic TG off-time to recharge BOOST capacitor when VIN ≈ VOUT - maintains regulation down to 99% duty cycle. |
| Robust Power-Good Monitoring | ±10% trip accuracy with 2.5% hysteresis and 25µs fault reporting delay - enables precise sequencing and avoids false triggers during transients. |
Applications
| Automotive Always-On Systems | Battery-Powered Digital Devices |
|---|---|
|
Use Scenario: Powering infotainment, telematics, and ADAS modules that remain active during vehicle sleep mode. IC Role / Device Role / Timing Role: Primary 12V-to-3.3V/5V step-down controller with ultra-low 50μA quiescent current and robust cold-crank (4V) support. Use Value: Extends battery life over weeks of parking; eliminates need for external wake-up circuitry due to RUN pin's 7μA internal pull-up. |
Use Scenario: Regulating power for portable test equipment, handheld medical monitors, and ruggedized IoT edge nodes. IC Role / Device Role / Timing Role: High-efficiency synchronous buck controller supporting Li-ion (3.0–4.2V) and 2S/3S pack inputs (6–12.6V). Use Value: Delivers >90% efficiency at 100mA–2A loads while maintaining <10mV output ripple in Forced CCM mode for noise-sensitive analog circuits. |
| Distributed DC Power Systems | Industrial Control & PLC Modules |
|
Use Scenario: Intermediate bus conversion in 48V data center rack PDUs or telecom shelf power distribution. IC Role / Device Role / Timing Role: 48V-to-12V/5V primary controller with phase-lockable 750kHz operation to minimize magnetics size and EMI. Use Value: Enables compact, high-density designs using small 4.7µH inductors and 22µF ceramic output caps; EXTVCC allows self-biasing from downstream rails. |
Use Scenario: Powering FPGA I/O banks, ADC/DAC references, and isolated communication interfaces in factory automation controllers. IC Role / Device Role / Timing Role: Precision 0.8V reference-based controller with TRACK/SS for coordinated multi-rail power-up and PGOOD for system health monitoring. Use Value: Ensures deterministic power sequencing across 3.3V, 1.8V, and 1.2V domains; ±10% PGOOD accuracy meets IEC 61000-4-2 immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640S | Integrated 4A power stage; 3.4V–42V input; 2.5μA IQ; fixed 2.2MHz frequency; no EXTVCC or TRACK/SS. | Better for space-constrained, medium-power apps where integration outweighs flexibility; lacks multi-rail tracking and external bias option. | Choose LT8640S if board area is critical and 42V max input suffices; LTC3891EFE#PBF preferred for >42V, multi-rail coordination, or external bias needs. |
| MP2491 | Monolithic 3A buck; 4.5V–60V input; 75μA IQ; 100kHz–2.5MHz freq; no PGOOD, no current-sense threshold selection. | Lower BOM cost for basic point-of-load; lacks precision PGOOD, soft-start control, and configurable light-load modes. | Choose MP2491 for cost-sensitive, non-safety-critical 3A loads; LTC3891EFE#PBF required for automotive-grade sequencing, low-IQ battery hold-up, or design flexibility. |
Compared with LT8640S and MP2491, the LTC3891EFE#PBF offers superior design adaptability through its external MOSFET drive, three-level current limit, EXTVCC biasing, and TRACK/SS-controlled sequencing - making it uniquely suited for high-reliability, multi-rail, and wide-input industrial and automotive platforms.
Availability
LTC3891EFE#PBF is available at Aetrix Electronics and suitable for automotive always-on systems, battery-powered digital devices, and distributed DC power systems requiring stable component supply, extended temperature operation (–40°C to 125°C), and long-term lifecycle assurance.
Supply support for LTC3891EFE#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 full product support, documentation, and manufacturing continuity for all Linear ICs including the LTC3891 series.
The LTC3891 belongs to Linear's high-voltage synchronous controller product line, engineered specifically for demanding industrial, automotive, and telecom power applications where wide input range, ultra-low quiescent current, and robust protection features are mandatory.
FAQ
What is the maximum input voltage rating for the LTC3891EFE#PBF?
The LTC3891EFE#PBF has an absolute maximum input voltage (VIN) rating of 65V, with continuous operation specified from 4V to 60V. This enables reliable use in 48V industrial buses, 36V automotive systems, and battery stacks up to 16S Li-ion. Exceeding 65V risks permanent damage per Absolute Maximum Ratings.
How does the LTC3891EFE#PBF achieve 50μA quiescent current?
The LTC3891EFE#PBF achieves 50μA no-load IQ through a dedicated low-power sleep mode activated when the ITH voltage drops below 0.425V. In this state, most internal circuitry-including gate drivers and oscillator-is disabled while retaining core regulation readiness, enabling rapid wake-up without sacrificing battery longevity in always-on applications.
Can the LTC3891EFE#PBF be synchronized to an external clock?
Yes, the LTC3891EFE#PBF supports external synchronization via the PLLIN/MODE pin. When an external clock signal (75–750kHz) is applied, the internal phase-locked loop aligns the rising edge of the TG signal to the external clock's rising edge - reducing EMI in noise-sensitive systems and enabling multi-phase interleaving without additional timing ICs.
What package type and thermal performance does the LTC3891EFE#PBF use?
The LTC3891EFE#PBF uses a 20-lead plastic TSSOP (FE package) with an exposed thermal pad (Pin 21) that must be soldered to SGND. Its thermal resistance is θJA = 38°C/W, enabling operation up to 125°C junction temperature at moderate power levels - verified per the datasheet's thermal characterization and JEDEC JESD51-7 testing methodology.
Does the LTC3891EFE#PBF support output voltage tracking during start-up?
Yes, the LTC3891EFE#PBF supports precise output voltage tracking via the TRACK/SS pin. By connecting an external resistor divider from a master supply to TRACK/SS, the LTC3891EFE#PBF regulates its VFB to match the master rail's voltage ramp - ensuring controlled, glitch-free power sequencing across multiple voltage domains in complex systems.
LTC3891EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-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):
- 4V ~ 60V
- Frequency - Switching:
- 105kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99%
- 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:
- 20-TSSOP-EP
LTC3891EFE#PBF FAQ
1.How can I place an order for LTC3891EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891EFE#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 LTC3891EFE#PBF reliable?
The price and inventory of LTC3891EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891EFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3891EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891EFE#PBF?
LTC3891EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891EFE#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 LTC3891EFE#PBF?
For technical support, including LTC3891EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891EFE#PBF requirements.
6.How does Aetrix verify that LTC3891EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3891EFE#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 LTC3891EFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3891EFE#PBF?
All LTC3891EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891EFE#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 LTC3891EFE#PBF part is unused and in its original packaging.
Return procedure for LTC3891EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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