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Analog Devices Inc. LTC3891MPFE#PBF
- Part No.:
- LTC3891MPFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3891MPFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:367
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Product details
Overview
LTC3891MPFE#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 switching up to 750kHz, and features 50μA no-load IQ - optimized for automotive always-on systems and battery-powered digital devices.
For engineers reviewing the LTC3891MPFE#PBF datasheet, LTC3891MPFE#PBF pinout, LTC3891MPFE#PBF application, or LTC3891MPFE#PBF equivalent, key selection criteria include its –55°C to 150°C extended temperature rating, selectable light-load modes (Burst/Pulse-Skipping/Forced CCM), RSENSE/DCR current sensing, and OPTI-LOOP® compensation for wide output capacitor/ESR tolerance.
Technical Context
The LTC3891MPFE#PBF implements a constant-frequency current-mode control architecture with an internal transconductance error amplifier (gm = 2 mmho) and precision 0.8V reference (±1.2mV over –55°C to 150°C). Its dual LDO system powers internal circuitry from either VIN (via INTVCC) or an external 4.7–14V source (EXTVCC), enabling high-efficiency biasing in multi-rail systems.
Light-load behavior is programmable via PLLIN/MODE: grounding selects Burst Mode (50μA IQ), tying to INTVCC forces continuous conduction, and applying 1.2V–(INTVCC–1.3V) enables pulse-skipping. Current limit threshold is selectable via ILIM (GND/FLOAT/INTVCC), setting VSENSE(MAX) to 22/43/64mV respectively - critical for MOSFET SOA protection under short-circuit conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports 12V/24V/48V intermediate buses and wide battery chemistries (LiFePO₄, lead-acid, multi-cell Li-ion). |
| Output Voltage Range | 0.8V to 24V - programmable via external resistor divider; 0.8V reference with ±1.2mV accuracy ensures tight regulation across temp. |
| No-Load Quiescent Current | 50μA - extends runtime in always-on automotive modules and portable instrumentation where standby power is critical. |
| Switching Frequency | 75kHz to 750kHz (phase-lockable); 350kHz/535kHz fixed options - balances EMI, efficiency, and inductor size for space-constrained designs. |
| Current Sense Threshold | Selectable 22/43/64mV - sets peak current limit without external gain stages; avoids MOSFET thermal runaway during overload. |
| Operating Temperature | –55°C to 150°C - qualified for under-hood automotive, industrial motor drives, and aerospace power subsystems. |
| Duty Cycle Max | 99% - enables ultra-low dropout operation (e.g., 12V→11.5V), essential for post-regulation in high-voltage systems. |
Pinout & Package
Package: 20-lead plastic TSSOP (FE package) with exposed pad (Pin 21 = SGND), θJA = 38°C/W. Requires soldering of exposed pad to PCB ground for thermal performance and noise immunity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TRACK/SS (Pin 1) | Soft-start & tracking control | 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) | VCO frequency programming | 20µA internal pull-up enables resistor-based frequency setting (50–900kHz); GND/INTVCC selects fixed 350/535kHz. |
| PLLIN/MODE (Pin 3) | Light-load mode selection | Ground = Burst Mode (50μA IQ); INTVCC = Forced CCM; 1.2V–(INTVCC–1.3V) = Pulse-Skipping - defines efficiency vs. ripple trade-off. |
| RUN (Pin 6) | Enable/shutdown control | 1.16V threshold disables regulation; 0.7V threshold shuts down entire IC (14μA IQ); 7µA internal pull-up allows floating for always-on use. |
| SENSE– / SENSE+ (Pins 7/8) | Differential current sense inputs | Supports RSENSE or DCR sensing; SENSE– supplies comparator bias when > INTVCC–0.5V - enables accurate current measurement at high common-mode voltages. |
| VFB (Pin 9) | Feedback voltage input | Compares output divider voltage to 0.8V reference; ±5nA input bias minimizes divider error - critical for high-resistance dividers. |
| ITH (Pin 10) | Error amplifier output | Controls peak inductor current; gm = 2 mmho enables OPTI-LOOP® compensation - stabilizes loop across diverse ceramic/polymer capacitor types. |
| PGOOD (Pin 11) | Power-good indicator | Open-drain output asserts low when VFB deviates >±10% from setpoint; 25µs fault delay prevents false triggering during transients. |
| TG (Pin 12) | Top gate driver output | Floating N-channel driver (2.5Ω pull-up/1.5Ω pull-down); 25ns rise/fall times support fast-switching GaN/SiC FETs. |
| SW (Pin 13) | Switch node connection | Connects to inductor and bootstrap capacitor; withstands –5V to 65V - accommodates high dV/dt ringing in high-frequency designs. |
| BOOST (Pin 14) | Bootstrap supply | Charges via external diode/capacitor; swings from INTVCC to (VIN + INTVCC) - sustains top-FET drive during high-duty-cycle operation. |
| BG (Pin 15) | Bottom gate driver output | Ground-referenced N-channel driver (2.4Ω pull-up/1.1Ω pull-down); 25ns rise/fall times minimize conduction losses. |
| INTVCC (Pin 16) | Internal LDO output | 5.1V ±3%, supplies drivers/control logic; requires ≥2.2µF ceramic decoupling to PGND - prevents gate drive collapse during load steps. |
| EXTVCC (Pin 17) | External bias input | Enables INTVCC sourcing from external 4.7–14V rail (e.g., downstream converter output), bypassing VIN LDO to improve system efficiency. |
| PGND (Pin 18) | Power ground return | Connects to bottom-FET source and CIN (–) - separates high-current paths from SGND to avoid noise coupling into sensitive analog circuits. |
| VIN (Pin 19) | Main input supply | Accepts 4–60V; requires local ceramic bypass to SGND - filters high-frequency switching noise before entering internal LDO. |
| ILIM (Pin 20) | Current limit range select | GND/FLOAT/INTVCC configures VSENSE(MAX) to 22/43/64mV - matches sense resistor value and MOSFET RDS(on) for optimal SOA margin. |
| SGND (Pins 2,3,21) | Small-signal ground | Must be routed separately from PGND and tied to CIN (–); exposed pad (Pin 21) must be soldered to PCB ground plane for thermal and EMI performance. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop response across wide output capacitance (10µF–1000µF) and ESR (0.5mΩ–100mΩ) - eliminates trial-and-error tuning for diverse capacitor families. |
| Programmable Light-Load Modes | Three distinct operating modes (Burst/Pulse-Skipping/Forced CCM) let designers optimize for ultra-low IQ, low ripple, or EMI compliance without changing hardware. |
| 99% Maximum Duty Cycle | Enables near-dropout regulation (e.g., 48V→47.5V), reducing heat in high-input-voltage applications where linear post-regulators would dissipate excessive power. |
| Output Overvoltage Protection | PGOOD monitors VFB with ±10% trip threshold and 2.5% hysteresis - provides fail-safe shutdown if feedback network fails open. |
| Low Shutdown IQ (<14μA) | Minimizes battery drain in systems requiring periodic wake-up (e.g., telematics, sensor nodes), extending shelf life and operational intervals. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering DSP, FPGA, and display controllers in vehicle head units with cold-crank (4.5V) and load-dump (60V) resilience. IC Role / Device Role / Timing Role: Primary 12V-to-3.3V/5V synchronous buck controller with Burst Mode for <50μA standby IQ during ignition-off. Use Value: Meets ISO 16750-2 automotive voltage transient requirements while maintaining <100mV output ripple in forced CCM during active operation. | Use Scenario: Generating isolated 24V-to-5V/3.3V rails for analog sensor front-ends and digital logic in factory automation controllers. IC Role / Device Role / Timing Role: High-efficiency, wide-input buck controller supporting 24V/48V DC bus inputs with programmable soft-start for inrush current limiting. Use Value: 0.8V reference accuracy (±1.2mV) ensures ADC reference stability; EXTVCC input allows biasing from local 5V rail to reduce system power loss. |
| Battery-Powered Test Equipment | Distributed Telecom Power |
Use Scenario: Portable oscilloscope or multimeter requiring long battery life and clean analog supply for precision ADCs. IC Role / Device Role / Timing Role: Dual-output controller (using TRACK/SS for sequencing) delivering 3.3V for logic and 5V for analog circuitry from single Li-ion cell stack. Use Value: 50μA no-load IQ extends battery runtime by >30% vs. standard controllers; OPTI-LOOP® ensures stable regulation with low-ESR polymer capacitors. | Use Scenario: Intermediate bus conversion in 48V telecom systems powering baseband processors and RF front-ends. IC Role / Device Role / Timing Role: 48V-to-12V primary buck controller with phase-lock capability to synchronize switching with system clock and reduce conducted EMI. Use Value: 75–750kHz synchronization range enables EMI filtering at fixed frequencies; 60V abs max rating handles telecom surge transients. |
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 |
|---|---|---|---|
| LTC3892MPFE#PBF | Dual-phase controller with current sharing; same 4–60V input, –55°C to 150°C rating, but adds phase interleaving and higher current capability. | Required for >30A output or lower output ripple; not drop-in - needs revised layout and loop compensation. | Choose LTC3892MPFE#PBF when scaling output current beyond single-phase limits or requiring interleaved ripple cancellation. |
| LM5116MHX/NOPB | 4.5–100V input, 50μA IQ, but only 0.8V reference accuracy ±2%, no EXTVCC option, and limited to –40°C to 125°C. | Suitable for cost-sensitive industrial applications without extended temp or ultra-precise regulation needs. | Choose LM5116MHX/NOPB for non-automotive 48V systems where 150°C operation and 0.8V ±1.2mV accuracy are not required. |
Compared with LTC3892MPFE#PBF and LM5116MHX/NOPB, the LTC3891MPFE#PBF uniquely balances ultra-wide temperature operation, precision 0.8V regulation, and flexible biasing (EXTVCC) in a single-phase controller - making it optimal for space-constrained, high-reliability automotive and industrial point-of-load designs.
Availability
LTC3891MPFE#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLC I/O modules, and battery-powered test equipment requiring stable component supply across extreme temperature ranges and long product lifecycles.
Supply support for LTC3891MPFE#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 legacy Linear parts including the LTC3891 series.
The LTC3891 product line was designed specifically for high-reliability, wide-input-voltage DC/DC conversion in automotive, industrial, and aerospace applications - emphasizing low IQ, extended temperature operation, and robust fault protection.
FAQ
What is the maximum junction temperature specification for the LTC3891MPFE#PBF?
The LTC3891MPFE#PBF is tested and guaranteed over a junction temperature range of –55°C to 150°C, with a maximum rated junction temperature of 150°C. This extended rating makes it suitable for under-hood automotive applications and high-ambient industrial environments where standard commercial or industrial grade controllers would fail.
How does the EXTVCC pin function in the LTC3891MPFE#PBF?
The EXTVCC pin on the LTC3891MPFE#PBF enables an external 4.7–14V supply to power the internal INTVCC LDO, bypassing the VIN-derived regulator. When EXTVCC exceeds 4.7V, the VIN LDO shuts off and the EXTVCC LDO activates, supplying 5.1V to internal circuitry - improving overall system efficiency when a clean, efficient auxiliary rail is available.
Can the LTC3891MPFE#PBF operate in Burst Mode at –55°C?
Yes, the LTC3891MPFE#PBF supports Burst Mode operation across its full specified temperature range of –55°C to 150°C. The 50μA no-load quiescent current and light-load efficiency characteristics are validated at both extremes, ensuring reliable low-power operation in cryogenic sensor systems or cold-climate automotive deployments.
What is the purpose of the ILIM pin on the LTC3891MPFE#PBF?
The ILIM pin on the LTC3891MPFE#PBF selects one of three current sense threshold levels: tying to GND sets VSENSE(MAX) = 22mV, FLOAT = 43mV, and INTVCC = 64mV. This allows precise matching of the current limit to the chosen sense resistor or DCR value - preventing false overcurrent trips while ensuring MOSFET SOA protection under fault conditions.
Does the LTC3891MPFE#PBF support synchronization to an external clock?
Yes, the LTC3891MPFE#PBF supports external clock synchronization via the PLLIN/MODE pin. Applying a 75–750kHz square wave to this pin locks the internal oscillator's rising edge to the external clock's rising edge, enabling deterministic switching timing across multiple converters - critical for EMI reduction in dense PCB layouts.
LTC3891MPFE#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:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LTC3891MPFE#PBF FAQ
1.How can I place an order for LTC3891MPFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891MPFE#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 LTC3891MPFE#PBF reliable?
The price and inventory of LTC3891MPFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891MPFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3891MPFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891MPFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891MPFE#PBF?
LTC3891MPFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891MPFE#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 LTC3891MPFE#PBF?
For technical support, including LTC3891MPFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891MPFE#PBF requirements.
6.How does Aetrix verify that LTC3891MPFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3891MPFE#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 LTC3891MPFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3891MPFE#PBF?
All LTC3891MPFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891MPFE#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 LTC3891MPFE#PBF part is unused and in its original packaging.
Return procedure for LTC3891MPFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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