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Analog Devices Inc. LTC3891IFE#PBF
- Part No.:
- LTC3891IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3891IFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,633
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Product details
Overview
LTC3891IFE#PBF from Analog Devices (formerly Linear Technology) is a high-performance, low-quiescent-current 60V synchronous step-down DC/DC controller driving all-N-channel MOSFETs. It features 50μA no-load IQ, 0.8V precision reference, phase-lockable 75–750kHz switching frequency, and wide 4V–60V input range - enabling robust power conversion in automotive always-on systems and battery-powered digital devices.
For engineers reviewing the LTC3891IFE#PBF datasheet, LTC3891IFE#PBF pinout, LTC3891IFE#PBF application, or LTC3891IFE#PBF equivalent, key selection criteria include its Burst Mode® operation for ultra-low IQ, selectable current limit via ILIM pin, OPTI-LOOP® compensation for broad output capacitor/ESR compatibility, and dual-package availability (TSSOP-20) with –40°C to 125°C operating range.
Technical Context
The LTC3891IFE#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 supports three light-load modes - Burst Mode®, pulse-skipping, and forced continuous - selected via PLLIN/MODE pin voltage level, with current foldback protection active during short-circuit conditions.
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. |
| No-Load Quiescent Current | 50μA - extends runtime in always-on battery systems such as telematics and ECU standby circuits. |
| Output Voltage Range | 0.8V to 24V - set by external resistor divider on VFB; enables single-controller support for core, I/O, and peripheral rails. |
| Switching Frequency Range | 75kHz to 750kHz (phase-lockable) - allows EMI optimization and inductor size reduction while maintaining stability across loads. |
| Reference Voltage Accuracy | ±1.2% over –40°C to 125°C - ensures tight output regulation without external trimming in industrial temperature environments. |
| Current Sense Threshold | 22mV to 85mV (selectable via ILIM pin) - provides scalable overcurrent protection for 5A–30A power stages using RSENSE or DCR sensing. |
| Power Good Threshold | ±10% of regulated VFB - delivers precise rail monitoring with 2.5% hysteresis to prevent false fault assertions during transients. |
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). Operating junction temperature range: –40°C to 125°C.
| 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 for supply tracking during startup. |
| FREQ (Pin 2) | Oscillator frequency programming | 20μA internal pull-up sets VCO frequency; grounded → 350kHz, tied to INTVCC → 535kHz, resistor-to-GND → 50–900kHz programmable range. |
| PLLIN/MODE (Pin 3) | Light-load mode selection & sync input | GND → Burst Mode®; INTVCC → forced continuous; 1.2V–(INTVCC–1.3V) → pulse-skipping; external clock → phase-locked operation. |
| RUN (Pin 6) | Digital enable/shutdown control | <1.16V → disable control loop; <0.7V → full shutdown (IQ <14μA); internal 7μA pull-up enables floating "always-on" configuration. |
| SENSE– / SENSE+ (Pins 7/8) | Differential current sense inputs | Support RSENSE or DCR sensing; SENSE– supplies comparator bias when > INTVCC – 0.5V; common-mode range up to 28V. |
| VFB (Pin 9) | Feedback voltage input | Compares output divider voltage to 0.8V reference; ±5nA input bias minimizes divider error; supports remote sensing. |
| ITH (Pin 10) | Error amplifier output & compensation node | Controls peak inductor current; connects to RC network for OPTI-LOOP® compensation; gm = 2 mmho enables wide capacitor/ESR stability. |
| PGOOD (Pin 11) | Open-drain power-good indicator | Pulled low when VFB deviates >±10% from target; 25μs fault delay prevents false triggering on fast transients. |
| TG (Pin 12) | Top N-MOSFET gate driver output | Floating driver with 2.5Ω pull-up / 1.5Ω pull-down; swing = INTVCC + SW node voltage; supports bootstrap capacitor recharge in dropout. |
| SW (Pin 13) | Switch node connection | Connects to inductor and bootstrap capacitor; withstands –5V to 65V; critical for layout separation between power and signal grounds. |
| BOOST (Pin 14) | Bootstrap supply for top 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 output | Ground-referenced driver with 2.4Ω pull-up / 1.1Ω pull-down; drives synchronous rectifier with fast 25/13 ns rise/fall times. |
| INTVCC (Pin 16) | Internal LDO output (5.1V) | Supplies gate drivers and control logic; requires ≥2.2µF ceramic decoupling to PGND; bypassed by EXTVCC when >4.7V. |
| EXTVCC (Pin 17) | External bias input for INTVCC LDO | Enables high-efficiency biasing from secondary regulator output; switchover hysteresis = 250mV; absolute max = 14V. |
| PGND (Pin 18) | Power ground return | Connects to bottom MOSFET source and CIN (–) terminal; must be separate from SGND except at single-point star ground. |
| VIN (Pin 19) | Main input supply | 4V–60V input; requires local ceramic bypass to SGND; powers VIN-based LDO when EXTVCC is inactive. |
| ILIM (Pin 20) | Current limit threshold select | GND → 22mV; FLOAT → 43mV; INTVCC → 64mV - sets maximum sense voltage for foldback protection without external components. |
| SGND (Pins 4,5,21) | Small-signal ground | Mandatory separate routing from PGND; pins 4/5 and exposed pad (21) must all connect to same low-noise SGND plane. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Enables stable loop response across 10µF–1000µF output capacitors and 1mΩ–100mΩ ESR, eliminating need for custom compensation per design. |
| Low Dropout Operation | 99% maximum duty cycle allows VOUT within 100mV of VIN - critical for 12V→11.9V post-regulation in automotive infotainment systems. |
| Programmable Light-Load Mode | Three distinct modes (Burst, pulse-skip, forced CCM) selectable via single pin voltage - balances efficiency, ripple, and EMI without firmware changes. |
| Output Overvoltage Protection | Hardware-based VOVL trips at +7% to +13% above regulated VFB - protects downstream ICs during feedback divider failure or load dump events. |
| Integrated Dual LDO Architecture | VIN- and EXTVCC-powered LDOs with automatic switchover reduce system-level power loss and eliminate need for discrete bias regulators. |
Applications
| Automotive Always-On Systems | Battery-Powered Digital Devices |
|---|---|
|
Use Scenario: Power management for telematics control units (TCUs) requiring 24-hour connectivity with <100μA system sleep current. IC Role / Device Role / Timing Role: Primary 24V→3.3V/5V buck controller managing main SoC and CAN transceiver rails during vehicle ignition-off state. Use Value: 50μA quiescent current directly enables multi-year battery life in disconnected parking mode without compromising wake-up responsiveness. |
Use Scenario: High-efficiency power stage for portable medical monitors with Li-ion battery (8.4V–12.6V) and dual-output requirements (3.3V logic, 5V USB). IC Role / Device Role / Timing Role: Synchronous step-down controller delivering up to 5A at 3.3V with soft-start and power-good sequencing for FPGA and ADC subsystems. Use Value: Adjustable current limit (22–85mV) and RSENSE/DCR flexibility allow optimized MOSFET selection for thermal and cost trade-offs in compact enclosures. |
| Distributed DC Power Systems | Industrial Embedded Controllers |
|
Use Scenario: Intermediate bus converter in 48V data center rack systems powering point-of-load regulators across multiple server blades. IC Role / Device Role / Timing Role: 48V→12V primary controller with phase-lock capability to synchronize switching frequency across parallel modules and reduce input ripple. Use Value: 75–750kHz synchronization range enables EMI filtering at fixed frequencies, simplifying compliance testing for Class A equipment. |
Use Scenario: Reliable 24V→5V conversion for PLC I/O modules operating in harsh factory environments with wide ambient temperature swings. IC Role / Device Role / Timing Role: Industrial-grade buck controller with –40°C to 125°C rating, output overvoltage protection, and robust current foldback under short-circuit faults. Use Value: ±1.2% reference accuracy and 0.01% load regulation ensure consistent sensor excitation and analog front-end performance across temperature and line variations. |
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 |
|---|---|---|---|
| LM5116PWPR | Higher 100μA IQ; fixed 100kHz–1MHz frequency; no Burst Mode®; requires external bootstrap diode. | Preferred for cost-sensitive industrial SMPS where light-load efficiency is secondary to BOM simplicity. | Choose LM5116PWPR when EXTVCC biasing and ultra-low IQ are not required, and board space permits discrete bootstrap diode placement. |
| MPQ4316GR-A | Integrated MOSFETs (6A); 40V max VIN; 30μA IQ; fixed 400kHz/800kHz options; no PLL or EXTVCC support. | Suitable for space-constrained consumer electronics with lower input voltage and moderate current needs. | Choose MPQ4316GR-A only for sub-40V, ≤6A applications where integrated FETs justify trade-offs in voltage range and feature set vs. LTC3891IFE#PBF. |
Compared with LM5116PWPR and MPQ4316GR-A, the LTC3891IFE#PBF uniquely combines 60V input capability, 50μA Burst Mode® IQ, EXTVCC biasing, and phase-lockable frequency - making it the only option among the three qualified for automotive always-on and high-voltage distributed power systems.
Availability
LTC3891IFE#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, long-term lifecycle support, and guaranteed –40°C to 125°C operation.
Supply support for LTC3891IFE#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 continuity, documentation, and technical support for the LTC® portfolio of high-performance power management ICs.
The LTC3891IFE#PBF belongs to Linear's high-voltage synchronous controller product line, designed specifically for demanding applications including automotive infotainment, industrial automation, and telecom infrastructure where wide input range, low IQ, and robust protection are mandatory.
FAQ
What is the maximum input voltage rating for the LTC3891IFE#PBF?
The LTC3891IFE#PBF has an absolute maximum input voltage rating of 65V, with a recommended operating range of 4V to 60V. This allows direct use with 48V industrial buses and 60V automotive transients while maintaining safe margin against overvoltage stress on internal circuitry and gate drivers.
Does the LTC3891IFE#PBF support both RSENSE and DCR current sensing?
Yes, the LTC3891IFE#PBF supports both RSENSE and DCR current sensing through its differential SENSE+ and SENSE– inputs. The device accommodates common-mode voltages up to 28V and includes internal offsets calibrated for accurate current measurement regardless of sensing method - enabling flexible PCB layout and thermal optimization.
How does the EXTVCC pin function on the LTC3891IFE#PBF?
The EXTVCC pin on the LTC3891IFE#PBF enables an external 4.5V–14V supply to power the internal INTVCC LDO, bypassing the VIN-based regulator. When EXTVCC exceeds 4.7V, the device automatically switches to this higher-efficiency bias source - reducing power loss and heat generation, especially useful when powering from a secondary switching rail.
What is the purpose of the TRACK/SS pin on the LTC3891IFE#PBF?
The TRACK/SS pin on the LTC3891IFE#PBF serves dual functions: soft-start control and supply tracking. An internal 10μA current source ramps an external capacitor to generate a controlled VOUT rise time; alternatively, connecting a resistor divider from another supply enables coordinated startup sequencing - essential for FPGA and processor power sequencing.
Can the LTC3891IFE#PBF operate in forced continuous conduction mode (FCCM)?
Yes, the LTC3891IFE#PBF can operate in forced continuous conduction mode by tying the PLLIN/MODE pin to INTVCC. In FCCM, inductor current is allowed to reverse, minimizing output voltage ripple and EMI - ideal for noise-sensitive applications like audio amplifiers and high-resolution ADCs where Burst Mode® ripple would degrade performance.
LTC3891IFE#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
LTC3891IFE#PBF FAQ
1.How can I place an order for LTC3891IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891IFE#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 LTC3891IFE#PBF reliable?
The price and inventory of LTC3891IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891IFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3891IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891IFE#PBF?
LTC3891IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891IFE#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 LTC3891IFE#PBF?
For technical support, including LTC3891IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891IFE#PBF requirements.
6.How does Aetrix verify that LTC3891IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3891IFE#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 LTC3891IFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3891IFE#PBF?
All LTC3891IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891IFE#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 LTC3891IFE#PBF part is unused and in its original packaging.
Return procedure for LTC3891IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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