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Analog Devices Inc. LTC3859ALHUHF#WPBF
- Part No.:
- LTC3859ALHUHF#WPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALHUHF#WPBF.pdf
- Description:
- 3X OUT, BUCK/BUCK/BOOST SYNC CNT
- Quantity:
- Payment:
- Shipping:
Inventory:104
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Product details
Overview
LTC3859ALHUHF#WPBF 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/boost outputs, and operation from 4.5V–38V input (or 2.5V post-startup). It enables cold-crank regulation in automotive start-stop systems.
For engineers reviewing the LTC3859ALHUHF#WPBF datasheet, LTC3859ALHUHF#WPBF pinout, LTC3859ALHUHF#WPBF application, or LTC3859ALHUHF#WPBF equivalent, key selection criteria include its AEC-Q100 qualification, 38-lead 5mm × 7mm QFN package with –40°C to 150°C operating range, triple-output phase-lockable architecture up to 850kHz, and support for RSENSE/DCR current sensing across all channels.
Technical Context
The LTC3859ALHUHF#WPBF implements constant-frequency current-mode control with independent ITH-based transconductance amplifiers per channel, enabling precise current limit setting and OPTI-LOOP compensation for wide output capacitance/ESR tolerance. Its dual-buck-plus-boost topology supports independent voltage regulation with dedicated feedback references (0.8V for bucks, 1.2V for boost) and separate RUN pins for per-channel enable/disable.
It integrates three high-current gate drivers (TG/BG) with matched rise/fall times (16–28ns), programmable switching frequency (50kHz–900kHz), and selectable light-load modes (Burst, pulse-skipping, forced continuous) via PLLIN/MODE. The device supports 100% duty cycle in boost mode and 99% in buck dropout, with integrated overvoltage protection on VFB1 and VFB3.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller - enables independent regulation of two step-down and one step-up rails from single input. |
| Input Voltage Range | 4.5V to 38V main bias; operates down to 2.5V post-startup when biased from boost output or auxiliary supply - supports automotive cold-crank conditions. |
| Quiescent Current | 28µA in Burst Mode with one channel active - extends battery runtime in always-on systems without compromising startup capability. |
| Output Voltage References | 0.8V ±1.2mV (buck), 1.2V ±18mV (boost) - ensures tight output regulation across temperature and load for precision power rails. |
| Switching Frequency | Programmable 50kHz–900kHz; phase-lockable 75kHz–850kHz - allows EMI optimization and synchronization with system clocks. |
| Package & Temp Grade | 38-lead 5mm × 7mm QFN; AEC-Q100 qualified, –40°C to +150°C junction - suitable for under-hood automotive applications requiring high reliability. |
| Current Sensing | RSENSE or DCR sensing supported on all three channels - provides flexibility in layout and thermal management for high-current designs. |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed PGND pad (Pin 39), rated for θJA = 34.7°C/W and TJMAX = 150°C. Exposed pad must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW2, SW3 | Switch node connections | Direct connection points to inductor terminals; require low-inductance routing to minimize switching losses and EMI. |
| TG1, TG2, TG3 | Top-gate N-MOSFET drivers | Floating high-side gate drives with INTVCC-referenced swing; support 100% duty cycle in boost mode. |
| BG1, BG2, BG3 | Bottom-gate N-MOSFET drivers | Ground-referenced synchronous drivers; pull to PGND with 1.1–2.4Ω on-resistance for efficient turn-off. |
| VFB1, VFB2, VFB3 | Feedback inputs | Monitor regulated output via resistor dividers; buck channels use 0.8V reference, boost uses 1.2V reference. |
| RUN1, RUN2, RUN3 | Per-channel enable inputs | Digital control pins with 1.18–1.33V rising threshold; independent shutdown enables sequencing and power domain isolation. |
| PLLIN/MODE | Mode selection & sync input | Selects Burst Mode (ground), pulse-skipping (1.2V–INTVCC–1.3V), or forced continuous (INTVCC); accepts external clock for synchronization. |
| PGOOD1 | Power-good indicator | Open-drain output asserting low when VFB1 deviates >±10% from setpoint - enables system-level fault detection and sequencing. |
| OV3 | Boost overvoltage flag | Open-drain output pulled low when VFB3 exceeds +10% of setpoint - provides dedicated boost rail fault signaling. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– | Differential current sense inputs | Support RSENSE or DCR sensing; SENSE3+ supplies current to comparator, enabling accurate boost current limiting. |
| INTVCC | Internal LDO output | 5.4V ±0.2V regulated supply powering internal logic and gate drivers; requires ≥4.7µF ceramic decoupling to PGND. |
| VBIAS | Main bias input | Primary supply input (4.5V–38V); powers internal LDO and enables operation down to 2.5V after startup when externally biased. |
| EXTVCC | External bias input | Alternative power source for INTVCC; activates internal LDO switchover at 4.7V, reducing power loss when auxiliary supply is available. |
Key Features
| Feature | Design Value |
|---|---|
| Low-IQ Burst Mode | 28µA quiescent current with one channel active - enables multi-week battery hold-up in always-on automotive modules. |
| Triple Independent Control | Separate RUN, ITH, TRACK/SS, and PGOOD/OV pins per channel - supports flexible power sequencing, dynamic margining, and fault isolation. |
| OPTI-LOOP Compensation | Adapts loop response to wide range of output capacitor ESR and capacitance values - eliminates need for custom compensation networks. |
| Cold-Crank Regulation | Maintains regulation during 2.5V input dips - critical for engine start-stop systems where battery voltage collapses transiently. |
| AEC-Q100 Automotive Qualification | Qualified to Grade H (–40°C to +150°C) with controlled manufacturing - meets reliability requirements for safety-critical vehicle subsystems. |
Applications
| Automotive Start-Stop Systems | Always-On Telematics Modules |
|---|---|
Use Scenario: Powering infotainment, ADAS sensors, and telematics ECUs during engine cranking and idle stop. IC Role / Device Role / Timing Role: Triple-output controller supplying 5V/8.5V buck rails and 10V boost rail from 12V battery, maintaining regulation through 2.5V cold-crank events. Use Value: Enables uninterrupted operation during engine restart; 28µA IQ extends backup battery life in GPS tracking units. |
Use Scenario: Providing always-on power to cellular modems, GNSS receivers, and CAN transceivers in fleet management devices. IC Role / Device Role / Timing Role: Generates isolated, sequenced rails with independent RUN control and PGOOD monitoring for system-level power management. Use Value: Supports low-power sleep states while retaining fast wake-up; AEC-Q100 qualification ensures field reliability in harsh environments. |
| Distributed DC Power Architectures | Multi-Rail Industrial Controllers |
Use Scenario: Converting 24V or 36V industrial bus to multiple point-of-load voltages for FPGA, DSP, and analog front-ends. IC Role / Device Role / Timing Role: Buck/buck/boost topology delivers 3.3V, 5V, and 12V rails simultaneously with phase-lockable switching to reduce input ripple. Use Value: Eliminates need for multiple discrete controllers; programmable frequency avoids sensitive EMI bands in dense PCB layouts. |
Use Scenario: Powering programmable logic controllers (PLCs) with mixed-voltage I/O, communication interfaces, and real-time processors. IC Role / Device Role / Timing Role: Supplies 1.2V core, 3.3V I/O, and 5V USB/communication rails using RSENSE current sensing for accurate load monitoring. Use Value: OPTI-LOOP compensation accommodates diverse capacitor types across rails; TRACK/SS pins enable coordinated soft-start across domains. |
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 |
|---|---|---|---|
| LTC3859AHUHF#PBF | Same pinout and functionality but rated for –40°C to +125°C (not AEC-Q100 qualified); higher 35µA Burst Mode IQ. | Suitable for industrial or commercial applications without automotive temperature or reliability requirements. | Select when AEC-Q100 qualification and 150°C operation are not required; lower cost alternative for non-automotive use. |
| LTC3859ALIUHF#WPBF | Identical architecture and pinout; differs only in temperature grade (–40°C to +125°C) and AEC-Q100 qualification level (Grade I vs Grade H). | Meets automotive requirements but lacks extended high-temp capability for under-hood placement. | Choose for cabin-mounted automotive modules where 125°C max junction is sufficient and cost sensitivity is higher. |
Compared with LTC3859AHUHF#PBF and LTC3859ALIUHF#WPBF, the LTC3859ALHUHF#WPBF uniquely combines AEC-Q100 Grade H qualification, –40°C to +150°C operation, and the lowest confirmed 28µA Burst Mode IQ - making it the sole option for high-reliability under-hood automotive power conversion.
Availability
LTC3859ALHUHF#WPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, always-on telematics modules, and distributed DC power architectures requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3859ALHUHF#WPBF 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-rail synchronous controllers optimized for automotive and industrial applications demanding ultra-low quiescent current, wide input range, and robust thermal performance.
FAQ
What is the maximum operating junction temperature for the LTC3859ALHUHF#WPBF?
The LTC3859ALHUHF#WPBF is rated for a maximum junction temperature of 150°C and is qualified to AEC-Q100 Grade H for automotive applications. Its thermal resistance θJA is 34.7°C/W in the 5mm × 7mm QFN package, requiring proper PCB copper area and thermal vias to maintain safe operation under full load at elevated ambient temperatures.
How does the LTC3859ALHUHF#WPBF achieve 28µA quiescent current?
The LTC3859ALHUHF#WPBF achieves 28µA quiescent current in Burst Mode with one channel active by dynamically disabling unused control circuitry, minimizing bias currents in the error amplifiers and oscillators, and employing optimized gate driver biasing - all verified in production test across the –40°C to +150°C range.
Can the LTC3859ALHUHF#WPBF regulate output voltage during cold-crank conditions?
Yes, the LTC3859ALHUHF#WPBF maintains regulation down to 2.5V input when biased from the boost output or an auxiliary supply, enabling continuous operation during automotive cold-crank events where battery voltage dips below 6V - a capability confirmed in the datasheet's "Outputs Remain in Regulation Through Cold Crank" feature.
What current sensing methods does the LTC3859ALHUHF#WPBF support?
The LTC3859ALHUHF#WPBF supports both RSENSE and DCR current sensing on all three channels. For buck channels, SENSE+ and SENSE– pins form a differential comparator input; for the boost channel, SENSE3+ supplies current to the comparator, enabling accurate current limiting with either method.
Is the LTC3859ALHUHF#WPBF pin-compatible with earlier LTC3859 variants?
Yes, the LTC3859ALHUHF#WPBF is fully pin-compatible with the LTC3859 and LTC3859A, sharing identical pinout, package dimensions, and functional behavior - differing only in reduced Burst Mode IQ (28µA vs 35µA) and AEC-Q100 Grade H qualification.
LTC3859ALHUHF#WPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- 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 ~ 36V
- Frequency - Switching:
- 50kHz ~ 900kHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Dead Time Control, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859ALHUHF#WPBF FAQ
1.How can I place an order for LTC3859ALHUHF#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALHUHF#WPBF 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 LTC3859ALHUHF#WPBF reliable?
The price and inventory of LTC3859ALHUHF#WPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALHUHF#WPBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALHUHF#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALHUHF#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALHUHF#WPBF?
LTC3859ALHUHF#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALHUHF#WPBF 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 LTC3859ALHUHF#WPBF?
For technical support, including LTC3859ALHUHF#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALHUHF#WPBF requirements.
6.How does Aetrix verify that LTC3859ALHUHF#WPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALHUHF#WPBF 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 LTC3859ALHUHF#WPBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALHUHF#WPBF?
All LTC3859ALHUHF#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALHUHF#WPBF, 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 LTC3859ALHUHF#WPBF part is unused and in its original packaging.
Return procedure for LTC3859ALHUHF#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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