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Analog Devices Inc. LTC3891MPUDC#PBF
- Part No.:
- LTC3891MPUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3891MPUDC#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:297
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Product details
Overview
LTC3891MPUDC#PBF from Analog Devices (formerly Linear Technology) is a high-performance, low-quiescent-current synchronous step-down DC/DC controller designed for wide-input automotive and industrial power systems. It drives all-N-channel MOSFETs, supports 4V–60V input, delivers 0.8V–24V programmable output, operates up to 750kHz with phase-lock capability, and features 50μA no-load IQ - enabling long battery runtime in always-on vehicle modules.
For engineers reviewing the LTC3891MPUDC#PBF datasheet, LTC3891MPUDC#PBF pinout, LTC3891MPUDC#PBF application, or LTC3891MPUDC#PBF equivalent, key selection criteria include its –55°C to 150°C extended temperature rating, OPTI-LOOP® compensation for broad capacitor/ESR compatibility, selectable light-load modes (Burst/Pulse-Skipping/Continuous), RSENSE or DCR current sensing, and integrated 5.1V INTVCC LDO with EXTVCC switchover.
Technical Context
The LTC3891MPUDC#PBF implements a constant-frequency current-mode control architecture with dual gate drivers (TG/BG), internal 0.8V reference, and precision power-good monitoring. Its PLLIN/MODE pin configures light-load behavior - Burst Mode® (ground), pulse-skipping (1.2V–INTVCC−1.3V), or forced continuous conduction (INTVCC).
It integrates an undervoltage lockout (3.8V typical), overvoltage protection (±10% at VFB), adjustable current limit via ILIM pin (three thresholds: 22/43/64mV), and dropout operation with 99% duty cycle. The TRACK/SS pin enables soft-start or supply tracking, while FREQ pin sets switching frequency from 50kHz to 900kHz using external resistor or fixed voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports 12V/24V/48V battery systems and intermediate bus rails without external pre-regulation. |
| No-Load Quiescent Current | 50μA - extends runtime in always-on automotive ECUs and battery-powered telemetry devices. |
| Output Voltage Range | 0.8V to 24V - programmable via external resistor divider; precise 0.8V ±1.2mV reference ensures tight regulation. |
| Switching Frequency | 50kHz to 900kHz - adjustable via FREQ pin; phase-lockable from 75kHz to 750kHz for EMI reduction and multi-rail synchronization. |
| Operating Temperature | –55°C to +150°C - qualified for under-hood automotive, aerospace, and harsh industrial environments. |
| Current Sensing | RSENSE or DCR - supports low-loss inductor-based sensing or discrete shunt; foldback protection limits MOSFET stress during short circuits. |
| Gate Drive Capability | TG/BG drivers with 2.5Ω/1.5Ω pull-up and 2.4Ω/1.1Ω pull-down - directly drives high-side and low-side N-MOSFETs with fast 13–25ns transitions. |
Pinout & Package
Package: 20-lead 3mm × 4mm plastic QFN (UDC) with exposed thermal pad (Pin 21 = SGND). Requires soldering of exposed pad to PCB ground for rated θJA = 43°C/W thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (PLLIN/MODE) | Mode Selection & Sync Input | Selects light-load operation (Burst/Pulse-Skipping/Continuous) or accepts external clock for phase-locking; determines system efficiency vs. noise trade-off. |
| 2,3,21 (SGND) | Small-Signal Ground | Must be routed separately from PGND; critical for noise immunity and stable current-sense amplifier operation. |
| 4 (RUN) | Digital Enable/Shutdown Control | Shuts down controller below 1.16V; reduces IQ to <14μA below 0.7V - enables precise UVLO implementation or microcontroller-controlled sequencing. |
| 5 (SENSE–), 6 (SENSE+) | Differential Current Sense Inputs | Measure voltage across sense resistor or DCR network; support three programmable current-limit thresholds via ILIM pin. |
| 7 (VFB) | Feedback Input | Compares output voltage (via resistive divider) to internal 0.8V reference; enables accurate regulation independent of load or line variation. |
| 8 (ITH) | Error Amplifier Output | Controls peak inductor current; used for loop compensation (OPTI-LOOP®) and transient response tuning across wide capacitor/ESR ranges. |
| 9 (PGOOD) | Open-Drain Power-Good Indicator | Asserts low when VFB deviates >±10% from setpoint - provides system-level fault signaling and power sequencing coordination. |
| 10 (TG), 13 (BG) | Top/Bottom Gate Drivers | Drive external N-MOSFETs; TG is floating (boost-referenced), BG is ground-referenced - enables synchronous rectification for >95% efficiency. |
| 11 (SW), 12 (BOOST) | Switch Node & Bootstrap Supply | SW connects to inductor; BOOST supplies TG driver via external capacitor/diode - enables high-side N-MOSFET drive without P-MOS or charge pump. |
| 14 (INTVCC), 15 (EXTVCC) | Internal LDO Outputs | INTVCC = 5.1V regulated supply; EXTVCC switchover (4.7V threshold) allows efficient sourcing from secondary rail - reduces heat and improves overall system efficiency. |
| 16 (PGND), 17 (VIN) | Power Ground & Main Input | PGND ties to bottom MOSFET source and CIN negative; VIN accepts full 4V–60V range - eliminates need for input pre-regulator in wide-vin applications. |
| 18 (ILIM), 19 (TRACK/SS), 20 (FREQ) | Configuration Inputs | ILIM selects current-limit threshold; TRACK/SS enables soft-start or supply tracking; FREQ sets oscillator frequency - all externally programmable without firmware. |
Key Features
| Feature | Design Value |
|---|---|
| Low-IQ Burst Mode® Operation | 50μA quiescent current at no load - preserves battery capacity in infotainment head units and telematics modules during sleep states. |
| OPTI-LOOP® Compensation | Allows stable loop response across ceramic, polymer, and electrolytic output capacitors with ESR from 0.5mΩ to 100mΩ - simplifies design reuse across platforms. |
| 99% Maximum Duty Cycle | Enables ultra-low dropout operation (e.g., 12V→11.5V) - critical for post-buck regulation in automotive start-stop and cold-crank scenarios. |
| Three-Threshold Current Limit | ILIM pin selects 22mV / 43mV / 64mV sense thresholds - matches optimal RSENSE values for 5A, 10A, or 15A designs without resistor recalculations. |
| Integrated EXTVCC Switchover | Automatically switches INTVCC sourcing from VIN LDO to external 5V/12V rail when EXTVCC > 4.7V - cuts controller self-heating by >60% in multi-rail systems. |
| –55°C to +150°C Rating | Qualified per AEC-Q100 Grade 1 (extended) - validated for engine control, ADAS camera modules, and industrial motor drives operating in extreme ambient conditions. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC Power Supply |
|---|---|
Use Scenario: Regulates 12V battery input to stable 3.3V/5V for microcontroller, CAN transceiver, and sensor interface in under-hood ECU. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing main logic rail with cold-crank tolerance and low-noise Burst Mode® during idle. Use Value: Maintains regulation down to 4.5V input during cranking; 50μA IQ prevents battery drain during weeks-long vehicle dormancy. |
Use Scenario: Generates isolated 12V and 24V rails from 48V DC distribution bus in modular industrial automation cabinet. IC Role / Device Role / Timing Role: High-efficiency step-down controller driving N-MOSFETs in compact, fanless power module with thermal derating to 150°C. Use Value: 60V max input eliminates need for front-end buck converter; EXTVCC switchover enables self-powered operation from secondary 12V rail. |
| Battery-Powered Telematics Gateway | Avionics Remote I/O Module |
Use Scenario: Powers LTE modem, GNSS receiver, and secure MCU from 3S Li-ion (9–12.6V) with strict 24-hour standby requirement. IC Role / Device Role / Timing Role: Wide-VIN buck controller with programmable soft-start and PGOOD sequencing for multi-rail power-up. Use Value: TRACK/SS pin enables controlled ramp to prevent inrush into large modem input capacitance; 50μA IQ enables >1-year battery life in sleep mode. |
Use Scenario: Supplies 5V/3.3V to ARINC 429 transceivers and FPGA in airborne remote data concentrator operating at −55°C to +70°C ambient. IC Role / Device Role / Timing Role: MIL-qualified synchronous controller with extended temperature grade and robust current limiting for safety-critical avionics. Use Value: –55°C to +150°C junction rating ensures reliability at altitude; current foldback protects against shorted ARINC lines without latch-off. |
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 |
|---|---|---|---|
| LM5116QPWPRQ1 | 4.5V–60V input, 50μA IQ, but lacks EXTVCC switchover and OPTI-LOOP®; uses traditional Type II/III compensation. | Requires external compensation network; less flexible for ceramic-capacitor-heavy designs; lower thermal robustness (–40°C to +125°C). | Preferred where cost sensitivity outweighs design flexibility and extended temperature needs. |
| MAX20006ATPA/VY+ | 3.5V–65V input, 28μA IQ, integrated MOSFETs (not controller), 2.2MHz fixed frequency - no external FET drive or frequency programming. | Not a controller: monolithic solution limits power scalability; unsuitable for >10A or custom FET selection (e.g., SiC/GaN). | Selected only for space-constrained, medium-power (<6A), fixed-frequency applications where layout simplicity is prioritized over efficiency tuning. |
Compared with LM5116QPWPRQ1 and MAX20006ATPA/VY+, the LTC3891MPUDC#PBF offers superior thermal resilience, programmable light-load behavior, and adaptive compensation - making it optimal for high-reliability, wide-temperature, and efficiency-critical synchronous buck implementations.
Availability
LTC3891MPUDC#PBF is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC power supplies, and battery-powered telematics gateways requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LTC3891MPUDC#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 semiconductors, serving automotive, industrial, communications, and aerospace markets.
The LTC3891MPUDC#PBF belongs to Linear's high-voltage synchronous controller product line, engineered specifically for rugged, wide-input, low-IQ power conversion in automotive and industrial systems demanding extended temperature operation and field reliability.
FAQ
What is the maximum input voltage rating for the LTC3891MPUDC#PBF?
The LTC3891MPUDC#PBF has an absolute maximum input voltage of 65V, with a recommended operating range of 4V to 60V. This allows direct connection to 48V battery systems and withstands automotive load-dump transients up to 65V without external clamping - a key advantage in engine control and commercial vehicle applications where input surge protection adds cost and board area.
How does the LTC3891MPUDC#PBF achieve 50μA quiescent current?
The LTC3891MPUDC#PBF achieves 50μA no-load IQ through integrated circuit-level optimizations including deep-sleep mode activation below 0.425V on the ITH pin, selective shutdown of bias currents in non-critical blocks, and ultra-low-leakage process technology. During Burst Mode® operation, internal circuitry powers down between switching bursts - verified across the full –55°C to +150°C range per datasheet Figure 3891 G17.
Can the LTC3891MPUDC#PBF be synchronized to an external clock?
Yes, the LTC3891MPUDC#PBF supports external synchronization via the PLLIN/MODE pin. When an external clock signal (75kHz–750kHz) is applied, the internal phase-locked loop aligns the rising edge of the TG gate drive to the external clock's rising edge - enabling EMI reduction in multi-rail systems and deterministic timing in time-sensitive applications like radar power supplies.
What is the purpose of the EXTVCC pin on the LTC3891MPUDC#PBF?
The EXTVCC pin on the LTC3891MPUDC#PBF allows the internal 5.1V INTVCC regulator to be powered from an external rail (e.g., a secondary 5V or 12V output) instead of VIN when EXTVCC exceeds 4.7V. This reduces power dissipation in the controller's internal LDO, lowers operating temperature, and improves overall system efficiency - especially beneficial in multi-output converters where one rail can power multiple controllers.
Does the LTC3891MPUDC#PBF support output voltage tracking during startup?
Yes, the LTC3891MPUDC#PBF supports precise output voltage tracking via the TRACK/SS pin. By connecting a resistor divider from a master supply to this pin, the LTC3891MPUDC#PBF regulates its VFB node to match the TRACK/SS voltage - ensuring coordinated power-up sequencing across multiple rails in complex systems such as FPGA-based industrial controllers or multi-core automotive domain ECUs.
LTC3891MPUDC#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN 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-QFN (3x4)
LTC3891MPUDC#PBF FAQ
1.How can I place an order for LTC3891MPUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891MPUDC#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 LTC3891MPUDC#PBF reliable?
The price and inventory of LTC3891MPUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891MPUDC#PBF is usually 5 days.
3.What payment methods are accepted for LTC3891MPUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891MPUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891MPUDC#PBF?
LTC3891MPUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891MPUDC#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 LTC3891MPUDC#PBF?
For technical support, including LTC3891MPUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891MPUDC#PBF requirements.
6.How does Aetrix verify that LTC3891MPUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3891MPUDC#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 LTC3891MPUDC#PBF meets industry standards.
7.What is the process for return or replacement of LTC3891MPUDC#PBF?
All LTC3891MPUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891MPUDC#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 LTC3891MPUDC#PBF part is unused and in its original packaging.
Return procedure for LTC3891MPUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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