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Analog Devices Inc. LTC3891EUDC#TRPBF
- Part No.:
- LTC3891EUDC#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3891EUDC#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:6,086
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Product details
Overview
LTC3891EUDC#TRPBF 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 delivers 0.8V–24V programmable output voltage with 50μA no-load IQ, phase-lockable 75–750kHz switching, and supports RSENSE/DCR current sensing in automotive always-on systems and battery-powered digital devices.
For engineers reviewing the LTC3891EUDC#TRPBF datasheet, LTC3891EUDC#TRPBF pinout, LTC3891EUDC#TRPBF application, or LTC3891EUDC#TRPBF equivalent, key selection criteria include its 4V–60V input range, 0.8V reference accuracy (±12mV), Burst Mode™ operation for ultra-low IQ, OPTI-LOOP® compensation, and 20-pin 3mm × 4mm QFN package with exposed thermal pad.
Technical Context
The LTC3891EUDC#TRPBF implements a constant-frequency current-mode control architecture with dual gate drivers (TG/BG), internal 5.1V LDO (INTVCC), and selectable light-load modes via PLLIN/MODE pin - enabling Burst Mode™, pulse-skipping, or forced continuous conduction. Its error amplifier features OPTI-LOOP® compensation for stable loop response across wide output capacitance and ESR ranges.
It integrates precision 0.8V feedback reference (±12mV over temperature), power-good monitoring (±10% trip threshold), output overvoltage protection, and adjustable current limit via ILIM pin (three thresholds: 22/43/64mV). The controller supports dropout operation up to 99% duty cycle and includes dedicated TRACK/SS pin for soft-start or supply tracking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports wide intermediate bus voltages and 12V/24V/48V battery chemistries without external regulators. |
| Output Voltage Range | 0.8V to 24V - set by external resistor divider; regulated by precision 0.8V ±12mV reference. |
| No-Load Quiescent Current | 50μA - enables multi-day runtime in battery-backed always-on applications (e.g., telematics, infotainment standby). |
| Switching Frequency Range | 75kHz to 750kHz - phase-lockable to external clock or programmable via FREQ pin resistor (50–900kHz). |
| Current Sense Threshold | 22mV / 43mV / 64mV - selected by ILIM pin connection (GND/FLOAT/INTVCC); enables accurate current limiting across load conditions. |
| Power Good Accuracy | ±10% at VFB - provides reliable system-level power sequencing and fault detection without external comparators. |
| Duty Cycle Max | 99% - supports ultra-low dropout operation (e.g., 12V→11.5V conversion) without requiring external bias supplies. |
Pinout & Package
Package: 20-lead 3mm × 4mm plastic QFN (UDC) with exposed thermal pad (Pin 21 = SGND), rated for –40°C to +125°C junction temperature (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SGND (Pins 2, 3, 21) | Small-signal ground reference | Mandatory separate routing from PGND; exposed pad must be soldered to PCB ground for thermal and noise performance. |
| RUN (Pin 4) | Digital enable/shutdown control | 1.16V threshold for control-loop disable; 0.7V threshold for full shutdown (<14μA IQ); internal 7μA pull-up enables floating-for-always-on use. |
| TRACK/SS (Pin 19) | Soft-start and supply tracking input | Internal 10μA current source ramps external capacitor; regulates VFB to TRACK/SS voltage until ≥0.8V - enables controlled startup or rail tracking. |
| ITH (Pin 8) | Error amplifier output & compensation node | Directly sets peak inductor current; connects to RC network for OPTI-LOOP® compensation - stabilizes loop across diverse output caps. |
| PLLIN/MODE (Pin 1) | Light-load mode selection & sync input | GND = Burst Mode™; INTVCC = forced CCM; 1.2V–(INTVCC–1.3V) = pulse-skipping; external clock = PLL sync (75–750kHz). |
| TG / BG (Pins 10 / 15) | Top/bottom N-MOSFET gate drivers | TG: floating driver (SW-referenced, 2.5Ω pull-up); BG: ground-referenced (1.1Ω pull-down); both support fast transitions (≤25ns). |
| SENSE+ / SENSE– (Pins 6 / 5) | Differential current sense inputs | Measure RSENSE or DCR voltage drop; SENSE– powers comparator when > INTVCC – 0.5V - enables high-side sensing. |
| ILIM (Pin 18) | Current limit threshold select | GND/FLOAT/INTVCC selects max sense voltage (22/43/64mV) - sets overcurrent trip point independent of ITH voltage. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ Operation | Reduces no-load IQ to 50μA while maintaining regulation - extends battery life in always-on automotive ECUs and IoT edge nodes. |
| OPTI-LOOP® Compensation | Enables stable transient response across 10μF–1000μF output capacitors and 5mΩ–100mΩ ESR - eliminates iterative loop tuning for diverse BOMs. |
| Programmable Light-Load Modes | Selectable Burst Mode™, pulse-skipping, or forced CCM via single PLLIN/MODE pin - balances efficiency, ripple, and EMI for each application. |
| 99% Maximum Duty Cycle | Supports VIN-to-VOUT differentials as low as 0.5V without external bias - simplifies design for post-regulation in distributed power architectures. |
| Integrated INTVCC LDO with EXTVCC Switchover | Auto-selects between VIN-derived (4.85–5.35V) or external EXTVCC (≥4.7V) supply for gate drivers - improves efficiency when powering INTVCC from a downstream rail. |
Applications
| Automotive Infotainment Power Supply | Industrial Battery Backup System |
|---|---|
Use Scenario: Powering 3.3V/5V rails for head-unit microcontrollers and display interfaces in vehicles with 9–16V battery input and cold-crank down to 4V. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus to low-voltage logic rails; manages soft-start during ignition and tracks auxiliary supplies during sleep/wake transitions. Use Value: 50μA quiescent current prevents battery drain during weeks of vehicle inactivity; 60V abs-max rating withstands load-dump transients up to 65V. | Use Scenario: Providing regulated 12V output from 14.4V LiFePO4 battery to sustain PLC I/O modules during AC mains failure. IC Role / Device Role / Timing Role: High-efficiency step-down controller with adjustable current limit and PGOOD signaling to enable seamless switchover to backup power. Use Value: 0.8V reference accuracy (±12mV) ensures precise 12V regulation; output overvoltage protection safeguards connected field devices during battery overcharge events. |
| Telecom Remote Radio Unit (RRU) | Medical Portable Diagnostic Device |
Use Scenario: Generating 5V/3.3V from 48V intermediate bus in outdoor base station radios operating at –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Wide-input synchronous controller with phase-lock capability to synchronize switching to system clock - reducing conducted EMI in dense RF environments. Use Value: 75–750kHz PLL range allows EMI band avoidance; 20-pin QFN package enables compact layout near power inductors with minimal thermal resistance. | Use Scenario: Powering FPGA, ADC, and wireless SoC in handheld ultrasound scanners powered by 3S Li-ion (9–12.6V) with strict battery-life requirements. IC Role / Device Role / Timing Role: Low-IQ buck controller delivering 1.2V core and 3.3V I/O rails; uses TRACK/SS to sequence power-up and prevent inrush into sensitive analog front-ends. Use Value: Adjustable soft-start via external capacitor eliminates output overshoot; 0.8V reference tolerance ensures <±1% output accuracy critical for ADC reference stability. |
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 |
|---|---|---|---|
| LTC3892EUDC#TRPBF | Dual-output version with independent channel control, higher 100μA IQ, same 4–60V input and 0.8V reference. | Required for dual-rail systems (e.g., 1.2V + 3.3V) where channel interleaving or phase-shifting is needed. | Select LTC3892EUDC#TRPBF only when dual outputs or channel synchronization are mandatory; otherwise LTC3891EUDC#TRPBF offers lower cost and IQ. |
| MP2918GL-Z | Monolithic 60V buck converter (integrated MOSFETs), 70μA IQ, fixed 0.8V reference, no PLL sync or TRACK/SS pin. | Suitable for space-constrained designs where external FETs are undesirable and light-load efficiency is secondary to BOM count. | Choose MP2918GL-Z for simplified layout and reduced component count; avoid if programmable frequency, soft-start, or ultra-low IQ (<60μA) are required. |
Compared with LTC3892EUDC#TRPBF and MP2918GL-Z, the LTC3891EUDC#TRPBF uniquely balances ultra-low 50μA quiescent current, flexible light-load mode selection, and precision 0.8V reference in a single-output controller - making it optimal for battery-sensitive, single-rail industrial and automotive applications where external FETs provide thermal and efficiency headroom.
Availability
LTC3891EUDC#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment power supplies, industrial battery backup systems, and telecom remote radio units requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.
Supply support for LTC3891EUDC#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 manufacturing continuity for the LTC portfolio.
The LTC3891 belongs to Linear's high-voltage synchronous controller product line, designed specifically for rugged, wide-input DC/DC conversion in automotive, industrial, and telecom infrastructure where reliability under voltage transients and ultra-low standby power are critical.
FAQ
What is the absolute maximum input voltage rating for the LTC3891EUDC#TRPBF?
The LTC3891EUDC#TRPBF has an absolute maximum input supply voltage (VIN) rating of 65V, as specified in the Absolute Maximum Ratings table. This allows safe operation during automotive load-dump transients and industrial surge events. Continuous operation is rated from 4V to 60V, and exceeding 65V may cause permanent damage. The device also specifies absolute maximum ratings for BOOST (71V), SW (65V), and other pins - all must remain within their individual limits during design.
How does the TRACK/SS pin function during startup in the LTC3891EUDC#TRPBF?
The TRACK/SS pin on the LTC3891EUDC#TRPBF controls output voltage ramping during startup by acting as a dynamic reference for the feedback loop. An internal 10μA current source charges an external capacitor connected from TRACK/SS to SGND, creating a linear voltage ramp. The LTC3891EUDC#TRPBF regulates VFB to match this rising voltage until it reaches or exceeds 0.8V - ensuring smooth, controlled VOUT rise without overshoot. It can also track another supply using a resistor divider.
Can the LTC3891EUDC#TRPBF operate with only ceramic output capacitors?
Yes, the LTC3891EUDC#TRPBF supports full stability with ceramic-only output capacitors due to its OPTI-LOOP® compensation architecture. Unlike conventional controllers requiring specific ESR for loop stability, the LTC3891EUDC#TRPBF's transconductance error amplifier allows stable operation across a wide range of capacitance (10μF–1000μF) and ESR (5mΩ–100mΩ), including zero-ESR MLCCs. This eliminates the need for aluminum or tantalum bulk capacitors in space-constrained designs.
What are the three current limit thresholds supported by the ILIM pin on the LTC3891EUDC#TRPBF?
The ILIM pin on the LTC3891EUDC#TRPBF selects one of three maximum current sense thresholds: 22mV when tied to SGND, 43mV when left floating (high-impedance), and 64mV when tied to INTVCC. These thresholds directly set the peak inductor current trip point in conjunction with the sense resistor or DCR network, enabling robust overcurrent protection tailored to different power levels and MOSFET RDS(on) values without changing external components.
Does the LTC3891EUDC#TRPBF support external clock synchronization, and what is the valid frequency range?
Yes, the LTC3891EUDC#TRPBF supports external clock synchronization via the PLLIN/MODE pin. When an external clock signal is applied, the internal phase-locked loop locks the TG switching edge to the rising edge of that clock. The valid synchronization frequency range is 75kHz to 750kHz, matching the device's native operating range. This feature reduces EMI by aligning switching noise to system clocks and enables multiphase interleaving in multi-controller systems.
LTC3891EUDC#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN 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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LTC3891EUDC#TRPBF FAQ
1.How can I place an order for LTC3891EUDC#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891EUDC#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 LTC3891EUDC#TRPBF reliable?
The price and inventory of LTC3891EUDC#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891EUDC#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3891EUDC#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891EUDC#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891EUDC#TRPBF?
LTC3891EUDC#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891EUDC#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 LTC3891EUDC#TRPBF?
For technical support, including LTC3891EUDC#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891EUDC#TRPBF requirements.
6.How does Aetrix verify that LTC3891EUDC#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3891EUDC#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 LTC3891EUDC#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3891EUDC#TRPBF?
All LTC3891EUDC#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891EUDC#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 LTC3891EUDC#TRPBF part is unused and in its original packaging.
Return procedure for LTC3891EUDC#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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