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Analog Devices Inc. LTC3891HUDC#TRPBF
- Part No.:
- LTC3891HUDC#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3891HUDC#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,476
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Product details
Overview
LTC3891HUDC#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 - enabling long battery runtime in automotive always-on systems and industrial power supplies.
For engineers reviewing the LTC3891HUDC#TRPBF datasheet, LTC3891HUDC#TRPBF pinout, LTC3891HUDC#TRPBF application, or LTC3891HUDC#TRPBF equivalent, key selection criteria include its wide VIN range, selectable light-load modes (Burst/Pulse-Skipping/CCM), OPTI-LOOP® compensation, precision 0.8V reference, and integrated power-good monitoring with overvoltage protection.
Technical Context
The LTC3891HUDC#TRPBF 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 LDO system powers internal circuitry from either VIN (via INTVCC) or an external 4.7–14V source (EXTVCC), enabling high-efficiency biasing from downstream rails.
It integrates a precision 0.8V feedback reference (±0.8% over temperature), programmable current limit via ILIM pin (three threshold levels: 22/43/64 mV), and adaptive gate drivers (TG/BG pull-up/down resistances ≤2.5Ω) optimized for fast switching with 25ns rise/fall times and <30ns dead-time control - critical for minimizing conduction loss and preventing shoot-through in high-current synchronous buck stages.
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 - set via external resistor divider on VFB; enables single-controller flexibility across logic, analog, and interface rails. |
| No-Load Quiescent Current | 50μA - extends battery life in always-on automotive modules (e.g., telematics, ADAS sensors) without sacrificing regulation accuracy. |
| Switching Frequency Range | 75kHz to 750kHz (phase-lockable) or 50kHz to 900kHz (fixed) - allows EMI optimization and inductor size reduction while maintaining stability across load transients. |
| Reference Voltage Accuracy | ±0.8% (0.792V–0.812V) over –40°C to 150°C - ensures tight output regulation in under-hood automotive environments. |
| Power-Good Threshold | ±10% of regulated VFB with 2.5% hysteresis - provides reliable system-level power sequencing and fault detection without external comparators. |
| Max Duty Cycle | 99% - enables ultra-low dropout operation (e.g., 12V→11.5V conversion) critical for high-VIN, low-ΔV applications. |
Pinout & Package
Package: 20-lead 3mm × 4mm plastic QFN (UDC) with exposed thermal pad (Pin 21 = SGND), rated for –40°C to +150°C junction temperature (H-grade).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PLLIN/MODE (1) | Mode selection & sync input | Selects Burst Mode (GND), pulse-skipping (1.2V–INTVCC–1.3V), or forced CCM (INTVCC); accepts external clock for phase-locking. |
| TG (10), BG (13) | Top/bottom gate drivers | Drive N-MOSFET gates with ≤2.5Ω on-resistance and 25ns transition times - minimizes switching loss and enables >5A continuous output. |
| SENSE+ (6), SENSE– (5) | Differential current sense inputs | Support RSENSE or DCR sensing; trip threshold set by ITH voltage and ILIM pin state (22/43/64 mV full-scale). |
| TRACK/SS (19) | Soft-start & tracking control | Internal 10μA pull-up charges external capacitor for linear soft-start; accepts resistor divider for supply tracking during power-up. |
| PGOOD (9) | Open-drain status output | Asserts low when VFB deviates >10% from target - enables safe processor reset or downstream enable sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop response across wide output capacitance (22µF–150µF) and ESR ranges without redesigning compensation network. |
| Selectably Optimized Light-Load Efficiency | Burst Mode (50μA IQ), pulse-skipping, or forced CCM - lets designers trade ripple/noise vs. efficiency based on end-application requirements. |
| Integrated Dual LDO Biasing | Auto-switches between VIN-powered and EXTVCC-powered INTVCC (switchover at 4.7V) - improves overall system efficiency by reusing regulated outputs as controller bias. |
| Robust Fault Protection | Includes output overvoltage protection (±10% VFB trip), current foldback limiting, and dropout detector that forces periodic top-FET off-time to recharge bootstrap capacitor. |
| Automotive-Grade Thermal Rating | H-grade (–40°C to +150°C TJ) with θJA = 43°C/W - qualified for under-hood deployment without derating in compact PCB layouts. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powers 3.3V/5V rails for MCU, CAN transceivers, and display controllers in head units with cold-crank (4.5V) and load-dump (60V) tolerance. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus from 12V battery; manages soft-start to prevent inrush into large capacitive loads. Use Value: 50μA quiescent current prevents battery drain during vehicle sleep mode; 60V abs-max rating withstands ISO 7637-2 pulses without external TVS. | Use Scenario: Generates isolated 12V and 24V auxiliary rails from 48V backplane in modular automation controllers operating in factory environments. IC Role / Device Role / Timing Role: High-voltage step-down controller driving discrete N-MOSFETs; uses PLLIN/MODE to synchronize switching with master clock for EMI reduction across multiple modules. Use Value: Phase-lockable frequency avoids beat frequencies; wide 4V–60V input accommodates brownout and overvoltage conditions common in industrial power distribution. |
| Portable Medical Diagnostic Device | Ruggedized Edge AI Gateway |
Use Scenario: Supplies clean 1.2V core and 3.3V I/O rails for ARM-based SoC in handheld ultrasound or glucose analyzers powered by 2-cell Li-ion (6–8.4V). IC Role / Device Role / Timing Role: Precision voltage controller with 0.8V reference and ±0.8% accuracy ensuring stable ADC/DAC reference voltages across temperature. Use Value: OPTI-LOOP® maintains transient response with ceramic output caps; TRACK/SS enables coordinated startup with FPGA configuration sequence. | Use Scenario: Powers 5V/12V rails for edge AI accelerators and Gigabit Ethernet PHYs in outdoor telecom cabinets with wide ambient temperature swings. IC Role / Device Role / Timing Role: High-reliability buck controller using EXTVCC to derive INTVCC from its own 5V output - eliminating dependency on noisy main 48V rail. Use Value: H-grade rating ensures operation at 125°C ambient; 99% duty cycle supports 48V→47V "near-dropout" biasing for low-noise analog subsystems. |
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 |
|---|---|---|---|
| LTC3892HUDC#TRPBF | Dual-output version with independent channel control, higher max frequency (850kHz), and enhanced current sharing; same package and pinout. | Suitable for dual-rail systems (e.g., 1.2V + 3.3V) requiring matched soft-start and tracking; adds complexity for single-output use. | Choose LTC3892HUDC#TRPBF only if dual-output capability or tighter cross-regulation is required - not a drop-in replacement for single-rail designs. |
| MP2918GL-Z | Monolithic 60V buck converter (integrated MOSFETs); lower IQ (25μA), fixed 500kHz fSW, no PLL or EXTVCC support. | Better for space-constrained, medium-current (<10A) applications where layout simplicity outweighs efficiency tuning flexibility. | Select MP2918GL-Z when board area is critical and external MOSFET drive is unnecessary; avoid when >10A, programmable fSW, or EXTVCC biasing is needed. |
Compared with LTC3892HUDC#TRPBF and MP2918GL-Z, the LTC3891HUDC#TRPBF offers unmatched configurability for high-current, high-reliability single-output systems - especially where automotive temperature range, precise light-load mode selection, and flexible biasing (VIN/EXTVCC) are mandatory design constraints.
Availability
LTC3891HUDC#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment power supplies, industrial PLC I/O modules, and portable medical diagnostic devices requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LTC3891HUDC#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3891 belongs to ADI's high-voltage monolithic and controller portfolio, designed specifically for robust, efficient DC/DC conversion in automotive, industrial, and telecom infrastructure where wide input range, low IQ, and extended temperature operation are essential.
FAQ
What is the maximum absolute input voltage rating for the LTC3891HUDC#TRPBF?
The LTC3891HUDC#TRPBF has an absolute maximum input supply voltage (VIN) of 65V. This rating applies across the full –40°C to +150°C operating junction temperature range and ensures survivability during automotive load-dump events per ISO 7637-2. Operation above 60V is not recommended for sustained periods due to increased power dissipation and potential thermal stress on internal LDOs and gate drivers.
How does the EXTVCC pin affect the operation of the LTC3891HUDC#TRPBF?
The EXTVCC pin on the LTC3891HUDC#TRPBF enables an external 4.7–14V supply to power the internal INTVCC LDO, bypassing the VIN-derived LDO. When EXTVCC exceeds 4.7V, the device automatically switches biasing to the external source - reducing power loss and improving overall system efficiency. This feature is commonly used to bias the LTC3891HUDC#TRPBF from its own regulated 5V or 12V output rail in multi-stage converters.
Can the LTC3891HUDC#TRPBF be synchronized to an external clock, and how is it configured?
Yes, the LTC3891HUDC#TRPBF supports external synchronization via the PLLIN/MODE pin. Applying a clean CMOS/TTL clock signal (75–750kHz) to this pin locks the internal oscillator's rising edge to the external clock's rising edge and forces forced continuous conduction mode. No additional components are required - the phase-locked loop handles frequency and phase alignment internally, enabling EMI reduction in multi-converter systems.
What is the purpose of the ILIM pin on the LTC3891HUDC#TRPBF, and what are its valid states?
The ILIM pin on the LTC3891HUDC#TRPBF selects one of three maximum current sense thresholds: 22mV (ILIM = GND), 43mV (ILIM = FLOAT), or 64mV (ILIM = INTVCC). This sets the full-scale voltage across the sense resistor or DCR network, directly determining the peak inductor current limit. The selection is static and must be made at PCB layout - no dynamic adjustment is supported during operation.
Does the LTC3891HUDC#TRPBF support output voltage tracking, and how is it implemented?
Yes, the LTC3891HUDC#TRPBF supports output voltage tracking via the TRACK/SS pin. Connecting an external resistor divider from a master supply to this pin causes the LTC3891HUDC#TRPBF output to ramp in proportion during startup. Alternatively, a capacitor from TRACK/SS to SGND enables soft-start, with the internal 10μA pull-up current generating a linear voltage ramp - allowing precise control of output slew rate without external timers or DACs.
LTC3891HUDC#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LTC3891HUDC#TRPBF FAQ
1.How can I place an order for LTC3891HUDC#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891HUDC#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 LTC3891HUDC#TRPBF reliable?
The price and inventory of LTC3891HUDC#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891HUDC#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3891HUDC#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891HUDC#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891HUDC#TRPBF?
LTC3891HUDC#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891HUDC#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 LTC3891HUDC#TRPBF?
For technical support, including LTC3891HUDC#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891HUDC#TRPBF requirements.
6.How does Aetrix verify that LTC3891HUDC#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3891HUDC#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 LTC3891HUDC#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3891HUDC#TRPBF?
All LTC3891HUDC#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891HUDC#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 LTC3891HUDC#TRPBF part is unused and in its original packaging.
Return procedure for LTC3891HUDC#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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