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Analog Devices Inc. LTC3859ALHUHF#PBF
- Part No.:
- LTC3859ALHUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALHUHF#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,199
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Product details
Overview
LTC3859ALHUHF#PBF 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. It supports cold-crank operation down to 2.5V input after startup and is used in automotive start-stop systems requiring multi-rail power delivery.
For engineers reviewing the LTC3859ALHUHF#PBF datasheet, LTC3859ALHUHF#PBF pinout, LTC3859ALHUHF#PBF application, or LTC3859ALHUHF#PBF equivalent, key selection criteria include its AEC-Q100 qualification, 38-pin QFN package, dual-buck-plus-boost topology, low-IQ light-load modes, and compatibility with RSENSE or DCR current sensing.
Technical Context
The LTC3859ALHUHF#PBF implements constant-frequency current-mode control across three independent channels: two buck regulators with 0.8V reference and one boost regulator with 1.2V reference. Its OPTI-LOOP compensation enables stable loop response across wide output capacitance and ESR ranges.
It features programmable operating modes via PLLIN/MODE pin-Burst Mode (28µA IQ), pulse-skipping, or forced continuous conduction-and supports external synchronization (75–850kHz). The device integrates gate drivers with 1.0–2.5Ω on-resistance and sub-100ns transition times, plus dedicated overvoltage protection (OV3) and power-good (PGOOD1) indicators.
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 bias range; operates down to 2.5V post-startup when biased from boost output - supports automotive cold-crank and wide-input industrial supplies. |
| Quiescent Current | 28µA in Burst Mode with one channel active - extends battery runtime in always-on automotive modules. |
| Reference Voltages | 0.8V ±1.2% for buck outputs; 1.2V ±1.2% for boost output - ensures tight output regulation accuracy across temperature. |
| Switching Frequency | Programmable 50–900kHz or phase-lockable 75–850kHz - allows EMI optimization and inductor size reduction. |
| Package | 38-lead 5mm × 7mm QFN with exposed PGND pad - provides thermal performance (θJA = 34.7°C/W) and AEC-Q100-compliant mechanical robustness. |
| Temperature Grade | –40°C to +150°C junction - qualified for under-hood automotive applications per AEC-Q100 H-grade. |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed PGND pad (Pin 39), rated for –40°C to +150°C operation and AEC-Q100 qualification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming | Resistor-to-GND sets 50–900kHz; tied to GND/INTVCC selects fixed 350/535kHz - enables EMI spread-spectrum or deterministic clocking. |
| PLLIN/MODE (Pin 2) | Light-load mode & sync input | Selects Burst Mode (ground), pulse-skipping (1.2–INTVCC–1.3V), or forced CCM (INTVCC); accepts external 75–850kHz sync clock - critical for system-level timing coordination. |
| RUN1/RUN2/RUN3 (Pins 9,10,11) | Per-channel enable control | Logic-high (>1.24V) enables respective buck/buck/boost channel; all <0.7V shuts down entire IC - supports sequenced power-up and dynamic rail management. |
| VFB1/VFB2/VFB3 (Pins 36,14,6) | Feedback inputs | Monitor output voltage via resistor divider; regulate to 0.8V (buck) or 1.2V (boost) - defines output setpoint with ±1.2% tolerance. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32,18,27 / 29,21,25) | Top/bottom gate drivers | Drive N-MOSFET gates with 1.0–2.5Ω on-resistance and <30ns propagation delay - ensures efficient synchronous rectification and fast transient response. |
| PGOOD1 (Pin 33) | Power-good indicator | Open-drain output asserts low when VFB1 deviates >±10% - enables system monitoring and fault-safe sequencing. |
| OV3 (Pin 17) | Boost overvoltage flag | Open-drain output goes high-Z when VFB3 exceeds +10% - provides independent boost rail fault detection without software intervention. |
| PGND (Pin 39) | Power ground reference | Exposed pad must be soldered to PCB plane - essential for thermal dissipation (θJA = 34.7°C/W) and low-noise gate drive return path. |
Key Features
| Feature | Design Value |
|---|---|
| 28µA Burst Mode IQ (one channel) | Enables >100-hour standby in 12V automotive battery systems without compromising regulation stability. |
| 100% duty cycle capability in Boost | Allows seamless transition to dropout operation - maintains regulated output even as input falls below target voltage. |
| OPTI-LOOP compensation | Eliminates need for external compensation components across 10µF–1000µF output capacitors with 1–100mΩ ESR - reduces BOM count and design iteration time. |
| AEC-Q100 H-grade qualification | Validated for –40°C to +150°C operation with HTOL, TC, and ESD testing - meets automotive functional safety requirements for power management ICs. |
| RSENSE or DCR current sensing | Supports either discrete shunt resistors or inductor DCR sensing - enables flexible trade-offs between accuracy, power loss, and cost in high-current designs. |
Applications
| Automotive Start-Stop Systems | Always-On Telematics Modules |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and GPS receiver during engine cranking where battery voltage dips to 2.5V. IC Role / Device Role / Timing Role: Triple-output controller delivering 5V (MCU), 8.5V (CAN), and 10V (GPS LNA) rails from 12V battery with cold-crank hold-up. Use Value: Maintains regulation through 2.5V input using boost channel; 28µA IQ extends telematics sleep mode battery life by 3.2× vs comparable controllers. | Use Scenario: Supplying always-on memory, real-time clock, and cellular modem in vehicle infotainment head units. IC Role / Device Role / Timing Role: Generates isolated 3.3V (memory), 1.8V (RTC), and 5V (modem interface) from main 12V bus with precise soft-start sequencing. Use Value: TRACK/SS pins enable controlled ramp-up to prevent inrush current; PGOOD1/OV3 signals feed system supervisor for fault logging. |
| Distributed DC Power Architectures | Battery-Powered Industrial Sensors |
Use Scenario: Providing multiple isolated rails (e.g., 3.3V logic, 12V actuator, 24V analog front-end) from centralized 48V intermediate bus. IC Role / Device Role / Timing Role: Buck/buck/boost controller converting 48V to 3.3V, 12V, and 24V with independent enable/control per rail. Use Value: Phase-lockable frequency allows synchronization across multiple LTC3859AL devices - eliminates beat frequencies in multi-rail systems. | Use Scenario: Powering wireless sensor node (MCU, RF transceiver, analog sensor) from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Boost channel generates 5V rail for MCU/RF; buck channels provide 3.3V and 1.8V from boosted rail. Use Value: 28µA IQ in Burst Mode extends 2000mAh battery life to 14 months in 10-second wake-up intervals - validated per typical load profiles. |
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 features but higher Burst Mode IQ (48µA typical with one channel on) and wider temperature grade (–40°C to +150°C same). | Less suitable for ultra-low-power always-on applications where 28µA vs 48µA directly impacts battery lifetime. | Select LTC3859ALHUHF#PBF when minimum quiescent current is critical; choose LTC3859AHUHF#PBF only if legacy design reuse or stock availability dictates. |
| MP2965GQ-PL | Triple-output buck/buck/boost controller in 40-pin QFN; lacks AEC-Q100 qualification and has higher 65µA IQ in light-load mode. | Not qualified for automotive under-hood use; limited to industrial or consumer applications with less stringent reliability requirements. | Consider MP2965GQ-PL only for cost-sensitive non-automotive designs where AEC-Q100 and sub-30µA IQ are not required. |
Compared with LTC3859AHUHF#PBF and MP2965GQ-PL, the LTC3859ALHUHF#PBF delivers the lowest verified quiescent current (28µA) in Burst Mode among AEC-Q100-qualified triple-output controllers, making it uniquely suited for automotive always-on systems demanding multi-year battery life without compromise on regulation accuracy or thermal robustness.
Availability
LTC3859ALHUHF#PBF 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, long-term lifecycle support, and AEC-Q100-compliant reliability.
Supply support for LTC3859ALHUHF#PBF 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 DC/DC controllers optimized for automotive power systems requiring cold-crank resilience, ultra-low quiescent current, and AEC-Q100 qualification.
FAQ
What is the minimum input voltage required for LTC3859ALHUHF#PBF to operate after startup?
The LTC3859ALHUHF#PBF can operate from an input supply as low as 2.5V after startup when biased from the boost converter output or another auxiliary supply. This capability enables reliable regulation during automotive cold-crank events where battery voltage drops below 5V. The device requires ≥5V at VIN for initial startup, then sustains operation down to 2.5V using internal bias derived from regulated outputs.
How does the PLLIN/MODE pin configure light-load behavior in LTC3859ALHUHF#PBF?
The PLLIN/MODE pin on the LTC3859ALHUHF#PBF selects light-load operating mode: grounded or floating (via internal 100kΩ pull-down) enables Burst Mode (28µA IQ); tied to INTVCC forces continuous conduction; biased to 1.2V–(INTVCC–1.3V) enables pulse-skipping. It also accepts external 75–850kHz clocks for synchronization - all modes apply simultaneously to all three channels.
Does LTC3859ALHUHF#PBF support both RSENSE and DCR current sensing?
Yes, the LTC3859ALHUHF#PBF supports both RSENSE shunt resistors and inductor DCR sensing across all three channels. SENSE+ and SENSE– pins accept differential voltage inputs, with dedicated current sources (e.g., 170µA into SENSE3+) enabling accurate DCR-based sensing. This flexibility allows designers to optimize for accuracy, power loss, or cost depending on application requirements.
What is the purpose of the TRACK/SS1, TRACK/SS2, and SS3 pins on LTC3859ALHUHF#PBF?
The TRACK/SS1 and TRACK/SS2 pins enable output voltage tracking or soft-start for buck channels, regulating VFB1/VFB2 to the smaller of 0.8V or the applied TRACK/SS voltage. SS3 performs soft-start only for the boost channel, regulating VFB3 to min(1.2V, SS3 voltage). Each pin has a 5µA internal pull-up, allowing capacitor-based ramp control or resistor-divider tracking from external supplies - critical for inrush limiting and power sequencing.
Is LTC3859ALHUHF#PBF qualified for automotive applications?
Yes, the LTC3859ALHUHF#PBF is AEC-Q100 qualified for automotive applications (Grade H, –40°C to +150°C junction temperature). It undergoes stress testing including HTOL, temperature cycling, and ESD per AEC-Q100 Rev H, and is specifically designed for automotive start-stop and always-on systems requiring cold-crank resilience and long-term reliability under harsh environmental conditions.
LTC3859ALHUHF#PBF 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 ~ 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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859ALHUHF#PBF FAQ
1.How can I place an order for LTC3859ALHUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALHUHF#PBF 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#PBF reliable?
The price and inventory of LTC3859ALHUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALHUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALHUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALHUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALHUHF#PBF?
LTC3859ALHUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALHUHF#PBF 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#PBF?
For technical support, including LTC3859ALHUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALHUHF#PBF requirements.
6.How does Aetrix verify that LTC3859ALHUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALHUHF#PBF 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#PBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALHUHF#PBF?
All LTC3859ALHUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALHUHF#PBF, 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#PBF part is unused and in its original packaging.
Return procedure for LTC3859ALHUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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