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Analog Devices Inc. LTC3891MPFE#TRPBF
- Part No.:
- LTC3891MPFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3891MPFE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,524
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Product details
Overview
LTC3891MPFE#TRPBF 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#TRPBF datasheet, LTC3891MPFE#TRPBF pinout, LTC3891MPFE#TRPBF application, or LTC3891MPFE#TRPBF equivalent, key selection criteria include its wide VIN range, selectable light-load modes (Burst/Pulse-Skipping/CCM), RSENSE/DCR current sensing, OPTI-LOOP® compensation, and –55°C to 150°C extended temperature rating.
Technical Context
The LTC3891MPFE#TRPBF implements a constant-frequency current-mode architecture with internal transconductance error amplifier (gm = 2 mmho), precision 0.8V reference (±0.8% over temp), and dual LDO power sources (VIN- or EXTVCC-derived INTVCC). Its PLLIN/MODE pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction - each altering inductor current behavior and efficiency trade-offs at light loads.
It integrates gate drivers with 2.5Ω TG pull-up, 1.5Ω TG pull-down, 2.4Ω BG pull-up, and 1.1Ω BG pull-down on-resistances; supports 99% maximum duty cycle for ultra-low dropout; and includes output overvoltage protection (±10% VFB trip), power-good monitoring, and adjustable soft-start via TRACK/SS pin with 10μA internal charge current.
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 runtime in always-on automotive and portable systems without compromising startup capability. |
| Output Voltage Range | 0.8V to 24V - programmable via external resistor divider; regulated by precision 0.8V ±0.8% reference. |
| Switching Frequency | 75kHz to 750kHz - phase-lockable to external clock or programmable via FREQ pin resistor (50–900kHz). |
| Operating Temperature | –55°C to +150°C - qualified for harsh-environment automotive under-hood and industrial control applications. |
| Current Sensing | RSENSE or DCR - configurable via ILIM pin (GND/FLOAT/INTVCC) to set max sense threshold at 22/43/64mV. |
| Gate Drive Capability | TG/BG drivers with <2.5Ω on-resistance and <30ns propagation delay - enables efficient drive of high-side and synchronous low-side N-MOSFETs. |
Pinout & Package
Package: 20-lead plastic TSSOP (FE package) with exposed pad (Pin 21 = SGND); thermal resistance θJA = 38°C/W; RoHS-compliant, lead-free finish.
| 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 for supply tracking. |
| FREQ (Pin 2) | Oscillator frequency programming | 20μA internal pull-up sets VCO frequency; GND = 350kHz, INTVCC = 535kHz, resistor-to-GND enables 50–900kHz tuning. |
| PLLIN/MODE (Pin 3) | Light-load mode selection | GND = Burst Mode®, INTVCC = forced CCM, 1.2V–(INTVCC–1.3V) = pulse-skipping - determines efficiency vs. ripple trade-off. |
| RUN (Pin 6) | Enable/shutdown control | 1.16V threshold disables regulation; 0.7V threshold shuts down entire IC, reducing IQ to <14μA. |
| SENSE– / SENSE+ (Pins 7/8) | Differential current sense inputs | Measure voltage across RSENSE or DCR network; bias current ≤±2μA ensures accuracy with high-impedance networks. |
| VFB (Pin 9) | Feedback input | Compares output voltage (via resistive divider) to 0.8V reference; ±5nA input bias minimizes divider error. |
| ITH (Pin 10) | Error amplifier output & compensation node | Controls peak inductor current; gm = 2 mmho enables OPTI-LOOP® compensation across wide ESR/capacitance ranges. |
| PGOOD (Pin 11) | Open-drain power-good indicator | Asserts low when VFB deviates >±10% from target; 25μs fault reporting delay ensures noise immunity. |
| TG (Pin 12) | Top-gate driver output | Floating driver with 2.5Ω pull-up / 1.5Ω pull-down; swings from SW to (SW + INTVCC) for high-side N-MOSFET drive. |
| SW (Pin 13) | Switch node connection | Connects to inductor and bootstrap capacitor; withstands –5V to 65V transient voltage during switching. |
| BOOST (Pin 14) | Bootstrap supply | Charged via external diode from INTVCC; supplies floating gate drive for TG; swing = INTVCC to (VIN + INTVCC). |
| BG (Pin 15) | Bottom-gate driver output | Ground-referenced driver with 2.4Ω pull-up / 1.1Ω pull-down; drives synchronous N-MOSFET source to PGND. |
| INTVCC (Pin 16) | Internal LDO output | 5.1V ±3% regulated supply for logic and drivers; sourced from VIN or EXTVCC (switchover at 4.7V). |
| EXTVCC (Pin 17) | External bias input | Enables higher-efficiency INTVCC sourcing from secondary rail (e.g., converter output); must not exceed 14V. |
| PGND (Pin 18) | Power ground return | Low-impedance return path for bottom MOSFET source and input capacitor negative terminal. |
| VIN (Pin 19) | Main input supply | Accepts 4V–60V; powers internal VIN-LDO for INTVCC when EXTVCC is inactive; requires local ceramic bypass. |
| ILIM (Pin 20) | Current limit threshold select | GND/FLOAT/INTVCC configures max sense voltage to 22/43/64mV - sets overcurrent protection level without external components. |
| SGND (Pins 2,3,21) | Small-signal ground | Must be routed separately from PGND; pins 2/3/21 electrically tied to minimize noise coupling into feedback/sense paths. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Transconductance error amplifier (gm = 2 mmho) enables stable loop response across wide output capacitor ESR and capacitance variations - eliminates trial-and-error compensation. |
| Selectably Optimized Light-Load Efficiency | Burst Mode® (50μA IQ), pulse-skipping, or forced CCM - chosen via single-pin configuration to match system noise, ripple, and battery-life requirements. |
| Ultra-Wide Input Range with Robust Protection | 4V–60V operation plus 65V absolute max input, output OVP (±10%), and current foldback - suitable for unregulated 48V telecom or automotive battery inputs. |
| Flexible Power Sourcing for INTVCC | Automatic switchover between VIN- and EXTVCC-derived 5.1V LDO (threshold = 4.7V) - allows efficient self-biasing from converter output rail. |
| Extended Temperature Grade | –55°C to +150°C junction rating with 150°C max TJ - validated for under-hood automotive, aerospace, and industrial motor control environments. |
| Programmable Soft-Start & Tracking | Internal 10μA TRACK/SS pull-up enables monotonic VOUT ramp with single capacitor; also supports precise multi-rail sequencing via external divider. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Powering FPGA, DSP, and memory in head-unit systems requiring stable 1.2V/3.3V/5V rails from 12V/24V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus to point-of-load voltages; handles 4V–60V transients including load dump. Use Value: 50μA quiescent current prevents battery drain during vehicle sleep; –55°C to 150°C rating ensures reliability in under-dash mounting locations. |
Use Scenario: Generating isolated 5V and 3.3V supplies for analog sensor front-ends and digital logic in factory-floor controllers exposed to wide ambient swings. IC Role / Device Role / Timing Role: High-efficiency, wide-input buck controller powering downstream LDOs and ADCs; supports 48V industrial bus input. Use Value: RSENSE/DCR sensing enables accurate current limiting in space-constrained modules; OPTI-LOOP® simplifies compensation for varying capacitive loads. |
| Battery-Powered Test Equipment | Distributed Telecom Power System |
|
Use Scenario: Portable oscilloscope or spectrum analyzer using Li-ion packs (8.4V–12.6V) to generate clean 3.3V/1.8V rails for RF and digital circuitry. IC Role / Device Role / Timing Role: Main step-down controller managing battery-to-logic conversion; operates in Burst Mode® during standby to maximize runtime. Use Value: 99% duty cycle enables operation near battery end-of-discharge; low-noise CCM mode available for sensitive analog sections. |
Use Scenario: Intermediate bus converter in 48V distributed power architecture supplying multiple point-of-load regulators across telecom shelf backplane. IC Role / Device Role / Timing Role: High-voltage synchronous controller stepping 48V down to 12V/5V intermediate rails; synchronized to system clock via PLLIN/MODE. Use Value: Phase-lockable 75–750kHz operation enables EMI reduction through clock harmonization; 60V abs max rating accommodates 48V surge events. |
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 |
|---|---|---|---|
| LTC3892MPUFD#TRPBF | Dual-output version with independent channel control, higher 1MHz max frequency, and enhanced current-mode stability; same 4V–60V input and –55°C to 150°C rating. | Required when two regulated outputs (e.g., 5V + 3.3V) must be generated from single input without cross-regulation issues. | Select LTC3892MPUFD#TRPBF only if dual-output capability and tighter cross-regulation are needed - adds complexity and cost versus single-channel LTC3891MPFE#TRPBF. |
| LM5116MHX/NOPB | 4.5V–100V input, 50μA IQ, but lacks Burst Mode®, uses voltage-mode control, and rated only to –40°C to 125°C; no EXTVCC option or OPTI-LOOP®. | Suitable for high-input-voltage industrial converters where extended temp is not required and lower-cost BOM is prioritized over light-load efficiency. | Choose LM5116MHX/NOPB for >60V input applications or cost-sensitive designs where –55°C operation and advanced light-load modes are unnecessary. |
Compared with LTC3892MPUFD#TRPBF, the LTC3891MPFE#TRPBF offers simpler layout and lower component count for single-rail needs; versus LM5116MHX/NOPB, it delivers superior low-temperature performance, finer light-load optimization, and more robust compensation flexibility - critical for automotive and precision industrial use.
Availability
LTC3891MPFE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment power supplies, industrial PLC I/O modules, and battery-powered test equipment requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LTC3891MPFE#TRPBF 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 qualification for legacy Linear parts including the LTC3891 family.
The LTC3891MPFE#TRPBF belongs to Linear's high-voltage synchronous controller product line, designed specifically for demanding automotive, industrial, and telecom applications requiring wide input range, ultra-low quiescent current, and extended temperature operation.
FAQ
What is the operating temperature range of the LTC3891MPFE#TRPBF?
The LTC3891MPFE#TRPBF is specified for operation from –55°C to +150°C junction temperature, with guaranteed performance across this full range. This extended grade makes it suitable for under-hood automotive, aerospace, and industrial environments where ambient temperatures exceed standard commercial or industrial limits. The device's thermal design - including exposed-pad TSSOP packaging and 38°C/W θJA - supports reliable operation at maximum rated TJ.
How does the LTC3891MPFE#TRPBF achieve 50μA quiescent current?
The LTC3891MPFE#TRPBF achieves 50μA no-load IQ primarily through Burst Mode® operation, which disables gate drivers and much of the internal circuitry between switching bursts. During sleep mode, the ITH pin is parked at 0.450V and the error amplifier is disconnected, minimizing active current draw. This low-IQ behavior is maintained across the full 4V–60V input range and is verified at –55°C to +150°C - enabling multi-year battery life in always-on systems.
Can the LTC3891MPFE#TRPBF be synchronized to an external clock?
Yes, the LTC3891MPFE#TRPBF supports external synchronization via the PLLIN/MODE pin. When an external clock signal (75kHz–750kHz) is applied to this pin, the internal phase-locked loop aligns the rising edge of the TG signal to the rising edge of the external clock. This feature enables EMI reduction through frequency harmonization and is fully functional across the device's –55°C to +150°C operating range.
What current sensing methods does the LTC3891MPFE#TRPBF support?
The LTC3891MPFE#TRPBF supports both RSENSE (shunt resistor) and DCR (inductor winding resistance) current sensing via differential SENSE+ and SENSE– inputs. The ILIM pin selects one of three maximum sense thresholds (22mV/GND, 43mV/FLOAT, or 64mV/INTVCC), allowing optimization for accuracy, power loss, or noise immunity. Input bias current is ≤±2μA, ensuring minimal error with high-impedance DCR networks.
Does the LTC3891MPFE#TRPBF include output overvoltage protection?
Yes, the LTC3891MPFE#TRPBF includes dedicated output overvoltage protection that monitors the VFB pin. If the feedback voltage deviates by more than ±10% from the regulated 0.8V reference - indicating an output overvoltage condition - the controller immediately disables switching and asserts PGOOD low. This protection operates independently of the main control loop and is effective across the full –55°C to +150°C temperature range.
LTC3891MPFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC3891MPFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891MPFE#TRPBF 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#TRPBF reliable?
The price and inventory of LTC3891MPFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891MPFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3891MPFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891MPFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891MPFE#TRPBF?
LTC3891MPFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891MPFE#TRPBF 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#TRPBF?
For technical support, including LTC3891MPFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891MPFE#TRPBF requirements.
6.How does Aetrix verify that LTC3891MPFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3891MPFE#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3891MPFE#TRPBF?
All LTC3891MPFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891MPFE#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LTC3891MPFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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