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Analog Devices Inc. LTC3859ALIUHF#TRPBF
- Part No.:
- LTC3859ALIUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALIUHF#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,951
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Product details
Overview
LTC3859ALIUHF#TRPBF from Analog Devices is a triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, featuring 28µA quiescent current in Burst Mode with one channel active, 0.8V/1.2V precision references for buck and boost outputs respectively, and phase-lockable switching up to 850kHz - deployed in automotive start-stop systems requiring cold-crank operation down to 2.5V input.
For engineers reviewing the LTC3859ALIUHF#TRPBF datasheet, LTC3859ALIUHF#TRPBF pinout, LTC3859ALIUHF#TRPBF application, or LTC3859ALIUHF#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification, dual-buck-plus-boost topology support, 38-lead QFN package with exposed PGND pad, and selectable light-load modes (Burst/Pulse-Skipping/Continuous).
Technical Context
The LTC3859ALIUHF#TRPBF implements constant-frequency current-mode control across three independent channels: two buck controllers with 0.8V reference and one boost controller with 1.2V reference, each using differential RSENSE or DCR current sensing. Its OPTI-LOOP compensation supports wide output capacitance/ESR ranges, while the PLLIN/MODE pin enables dynamic mode selection and external clock synchronization.
It features independent RUN pins per channel for sequencing, dedicated TRACK/SS inputs for soft-start and voltage tracking, and separate PGOOD1 and OV3 fault indicators. The gate drivers deliver 1.2Ω pull-up/pull-down resistance on TG3/BG3 for high-side/low-side boost FETs, with minimum on-times of 95ns (buck) and 120ns (boost), enabling high VIN-to-VOUT ratios and low dropout operation (up to 99% duty cycle).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Triple-output synchronous buck/buck/boost controller - enables compact multi-rail power architecture without discrete boost ICs. |
| Quiescent Current | 28µA (one channel active in Burst Mode) - extends battery runtime in always-on automotive modules. |
| Input Voltage Range | 4.5V to 38V bias; operates down to 2.5V after startup when biased from boost output - supports cold-crank and wide automotive supply range. |
| Output Voltage Range | Buck: 0.8V–24V; Boost: up to 60V - accommodates core logic, I/O, and high-voltage sensors in distributed power systems. |
| Switching Frequency | 75kHz–850kHz (phase-lockable); programmable 50kHz–900kHz via resistor - allows EMI optimization and inductor size reduction. |
| Package | 38-lead 5mm × 7mm QFN with exposed PGND pad - provides low thermal resistance (θJA = 34.7°C/W) and robust ground integrity for high-current switching. |
| AEC-Q100 Grade | Grade I (–40°C to +125°C junction) - qualified for automotive under-hood and infotainment applications. |
Pinout & Package
38-lead (5mm × 7mm) plastic QFN package with exposed PGND pad (Pin 39), rated for –40°C to +125°C operating junction temperature. Exposed pad must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming | Resistor-to-GND sets 50–900kHz; tied to GND/INTVCC for fixed 350/535kHz - enables EMI spread-spectrum or deterministic timing. |
| PLLIN/MODE (Pin 2) | Light-load mode select & sync input | GND = Burst Mode; INTVCC = forced continuous; 1.2V–(INTVCC–1.3V) = pulse-skipping; external clock = sync - critical for system-level power state coordination. |
| RUN1/RUN2/RUN3 (Pins 9,10,11) | Per-channel enable/disable | Thresholds at 1.18–1.33V rising edge; hysteresis 70mV - enables independent sequencing and fault isolation between rails. |
| VFB1/VFB2/VFB3 (Pins 36,14,6) | Feedback input | 0.8V reference for buck channels; 1.2V for boost - defines regulation setpoint with ±0.8% initial accuracy over temperature. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32,18,27 / 29,21,25) | High-current gate drivers | 1.2Ω pull-up/pull-down on boost drivers; 2.5Ω/1.5Ω on buck top/bottom - drives 10nC+ MOSFETs at 850kHz with <30ns propagation delay. |
| PGND (Pin 39) | Power ground return | Exposed thermal pad connected to source nodes of bottom FETs and CIN– - mandatory for thermal dissipation and noise immunity in high di/dt paths. |
Key Features
| Feature | Design Value |
|---|---|
| 28µA Burst Mode IQ (one channel) | Enables >100-hour standby in battery-backed telematics modules without compromising fast wake-up response. |
| 100% duty cycle capability in boost channel | Supports seamless transition from buck to boost operation during input voltage dips below regulated output (e.g., 12V battery drop to 6V while maintaining 10V rail). |
| OPTI-LOOP compensation | Eliminates loop stability re-tuning when changing output capacitor type (e.g., ceramic vs. polymer) or ESR across production batches. |
| Independent TRACK/SS inputs per channel | Allows synchronized soft-start of buck outputs to match an external master rail, preventing inrush current conflicts in multi-IC power trees. |
| AEC-Q100 Grade I qualification | Validated for automotive use with full temperature range testing, failure analysis, and process controls - reduces qualification burden for Tier 1 suppliers. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management during engine cranking where battery voltage drops to 2.5V for 50ms. IC Role / Device Role / Timing Role: Triple-output controller maintains stable 5V/8.5V/10V rails for MCU, CAN transceiver, and RF modem despite input collapse. Use Value: Cold-crank regulation ensures uninterrupted GPS/GSM connectivity and ECU operation without brownout resets. | Use Scenario: Long-term monitoring node powered by Li-ion cell with 3.0–4.2V range. IC Role / Device Role / Timing Role: Generates 3.3V buck rail for microcontroller, 5V buck for cellular module, and 12V boost for sensor excitation. Use Value: 28µA Burst Mode IQ extends operational life to >2 years on single 2000mAh cell with periodic wake-ups. |
| Distributed DC Power Architecture | Industrial Control I/O Modules |
Use Scenario: Central 24V bus powering multiple isolated subsystems in factory automation cabinet. IC Role / Device Role / Timing Role: Provides local 3.3V, 5V, and adjustable 15–28V rails directly at point-of-load, eliminating long DC distribution losses. Use Value: Dual-buck-plus-boost topology replaces three discrete regulators, reducing BOM count and PCB area by 40%. | Use Scenario: Programmable logic controller (PLC) backplane supplying 24V field power, 5V logic, and 12V analog sensor bias. IC Role / Device Role / Timing Role: Regulates three independent outputs with individual RUN pin control for hot-swap sequencing and fault containment. Use Value: Per-channel shutdown isolates faults without collapsing entire power tree - improves system MTBF and diagnostics. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3859AIFE#TRPBF | Same pinout and function but higher Burst Mode IQ (45µA typical with one channel on); TSSOP package (θJA = 25°C/W). | Preferred for cost-sensitive industrial designs where thermal margin is sufficient and leaded package eases rework. | Select when lower assembly cost and hand-solderability outweigh QFN thermal advantage. |
| MP2918GL-Z | Triple buck-only controller (no boost channel); 35µA IQ; 40V max input; 24-pin QFN. | Suitable only for multi-rail buck applications - cannot replace LTC3859ALIUHF#TRPBF in boost-required architectures like 12V-to-24V sensor bias. | Choose only if system requires three buck rails and no boost functionality; verify gate drive strength compatibility. |
Compared with LTC3859AIFE#TRPBF and MP2918GL-Z, the LTC3859ALIUHF#TRPBF uniquely combines AEC-Q100 qualification, integrated boost capability, and lowest IQ in Burst Mode - making it the sole option for automotive multi-rail systems needing cold-crank resilience and extended battery life.
Availability
LTC3859ALIUHF#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered telematics, and distributed DC power architectures requiring stable component supply, long-lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LTC3859ALIUHF#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3859AL product line delivers high-efficiency, multi-output synchronous controllers optimized for automotive and battery-critical applications demanding ultra-low quiescent current, wide input range, and robust fault protection.
FAQ
What is the minimum input voltage required for startup of the LTC3859ALIUHF#TRPBF?
The LTC3859ALIUHF#TRPBF requires a minimum 5V on VBIAS to initiate startup. Once running, it can sustain operation with VBIAS as low as 2.5V when biased from the boost output or another auxiliary supply - enabling reliable cold-crank performance in automotive applications where battery voltage dips transiently below 5V.
How does the LTC3859ALIUHF#TRPBF achieve 28µA quiescent current?
The LTC3859ALIUHF#TRPBF achieves 28µA quiescent current in Burst Mode by dynamically disabling internal circuitry - including oscillator, gate drivers, and error amplifiers - during light-load periods, while retaining feedback monitoring and fast wake-up capability. This behavior is confirmed in Electrical Characteristics Table (Page 4, Sleep Mode row) and applies specifically when only one channel is active.
Can the LTC3859ALIUHF#TRPBF drive high-side N-channel MOSFETs in the boost channel?
Yes, the LTC3859ALIUHF#TRPBF integrates floating high-side gate drivers (TG3 and BOOST3) capable of driving N-channel MOSFETs in the boost stage. The BOOST3 pin supplies charge pump voltage up to 76V, and TG3 delivers 1.2Ω pull-up/pull-down strength - verified in Absolute Maximum Ratings (Page 2) and Electrical Characteristics (Page 5, Gate Driver section).
What is the purpose of the EXTVCC pin on the LTC3859ALIUHF#TRPBF?
The EXTVCC pin on the LTC3859ALIUHF#TRPBF connects to an external 4.5–14V supply to power the INTVCC LDO, bypassing the internal VBIAS-regulated LDO. When EXTVCC exceeds 4.7V, it automatically takes precedence - improving efficiency and thermal performance in systems with available auxiliary rails, as specified in Electrical Characteristics (Page 5, INTVCC Linear Regulator section).
Is the LTC3859ALIUHF#TRPBF pin-compatible with earlier LTC3859 variants?
Yes, the LTC3859ALIUHF#TRPBF is fully pin-compatible with the LTC3859 and LTC3859A, as explicitly stated in the datasheet: "Compared to the LTC3859 and the LTC3859A, the LTC3859AL is fully pin-compatible, but with lower Burst Mode operation IQ (28µA with one channel on)." This enables drop-in replacement in existing designs targeting reduced quiescent current.
LTC3859ALIUHF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Buck-Boost, SEPIC
- Number of Outputs:
- 3
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 115kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99%, 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859ALIUHF#TRPBF FAQ
1.How can I place an order for LTC3859ALIUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALIUHF#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 LTC3859ALIUHF#TRPBF reliable?
The price and inventory of LTC3859ALIUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALIUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALIUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALIUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALIUHF#TRPBF?
LTC3859ALIUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALIUHF#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 LTC3859ALIUHF#TRPBF?
For technical support, including LTC3859ALIUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALIUHF#TRPBF requirements.
6.How does Aetrix verify that LTC3859ALIUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALIUHF#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 LTC3859ALIUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALIUHF#TRPBF?
All LTC3859ALIUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALIUHF#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 LTC3859ALIUHF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859ALIUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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