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Analog Devices Inc. LTC3859ALHUHF#TRPBF
- Part No.:
- LTC3859ALHUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALHUHF#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,693
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Product details
Overview
LTC3859ALHUHF#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 operation across 4.5V–38V input range - used in automotive start-stop systems requiring cold-crank regulation down to 2.5V.
For engineers reviewing the LTC3859ALHUHF#TRPBF datasheet, LTC3859ALHUHF#TRPBF pinout, LTC3859ALHUHF#TRPBF application, or LTC3859ALHUHF#TRPBF equivalent, key selection criteria include its triple-output topology, AEC-Q100 qualification, phase-lockable 75kHz–850kHz switching frequency, OPTI-LOOP compensation, and support for RSENSE or DCR current sensing in high-reliability power management designs.
Technical Context
The LTC3859ALHUHF#TRPBF implements constant-frequency current-mode control with independent ITH error amplifier outputs per channel, enabling precise current limit programming and transient response optimization via OPTI-LOOP. Its architecture supports three distinct regulation loops: two buck converters with 0.8V reference and one boost converter with 1.2V reference, each with dedicated SENSE+/– differential inputs and programmable soft-start.
It integrates three high-current gate drivers (TG/BG pairs) with matched rise/fall times (13–28ns), 100% duty cycle capability for the boost synchronous MOSFET even in Burst Mode, and dual bias options (VBIAS or EXTVCC) with automatic switchover at 4.7V. The PLLIN/MODE pin configures light-load behavior across Burst Mode, pulse-skipping, or forced continuous conduction.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller - enables compact multi-rail power supplies without external controllers. |
| Quiescent Current (Burst Mode, 1 channel) | 28µA - extends battery runtime in always-on automotive and portable systems. |
| Input Voltage Range | 4.5V to 38V (VBIAS); operates down to 2.5V post-startup when biased from boost output - supports cold-crank conditions. |
| Feedback References | 0.8V ±1.2mV (buck channels), 1.2V ±18mV (boost channel) - ensures tight output regulation across temperature. |
| Switching Frequency | 75kHz to 850kHz (phase-lockable); 50kHz to 900kHz (programmable via FREQ resistor) - balances efficiency, size, and EMI. |
| Current Sensing | RSENSE or DCR - allows flexible, low-loss inductor current monitoring with minimal BOM cost. |
| Package | 38-lead 5mm × 7mm QFN (UHF) with exposed PGND pad - provides low thermal resistance (θJA = 34.7°C/W) for high-power density layouts. |
| AEC-Q100 Grade | Grade H (–40°C to +150°C junction) - qualified for under-hood automotive applications including start-stop systems. |
Pinout & Package
38-lead (5mm × 7mm) plastic QFN package (UHF) with exposed PGND pad (Pin 39), requiring soldering to PCB for thermal and electrical performance. Pin pitch: 0.5mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming | Resistor-to-GND sets 50kHz–900kHz; tied to GND/INTVCC for fixed 350kHz/535kHz - enables EMI tuning and synchronization. |
| PLLIN/MODE (Pin 2) | Light-load mode & sync input | Selects Burst Mode (GND), pulse-skipping (1.2V–INTVCC–1.3V), or forced CCM (INTVCC); accepts external clock for phase-locking - critical for system-level timing coordination. |
| RUN1/RUN2/RUN3 (Pins 9,10,11) | Per-channel enable control | Logic-high (>1.24V) enables corresponding regulator; all <0.7V shuts down entire IC - supports sequenced power-up and dynamic rail management. |
| VFB1/VFB2/VFB3 (Pins 36,14,6) | Feedback voltage inputs | Monitor output voltage via resistive divider; regulate to 0.8V (buck) or 1.2V (boost) - defines final output accuracy and stability. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– (Pins 37,38,13,12,4,5) | Differential current sense inputs | Measure MOSFET current for cycle-by-cycle protection; support RSENSE or DCR sensing - enables accurate overcurrent limiting and current sharing. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32,36,27,33,25,29,31,35,28) | Top/bottom gate drivers | Drive N-MOSFET gates with 1.0–2.5Ω on-resistance and <30ns transition times - ensures efficient switching and low driver losses. |
| PGOOD1 (Pin 33) | Power-good indicator | Open-drain output asserting when VFB1 deviates >±10% - provides system-level fault signaling for buck1 only. |
| OV3 (Pin 17) | Boost overvoltage flag | Open-drain output asserting when VFB3 exceeds +10% - enables independent boost rail monitoring and safety shutdown. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP compensation | Allows stable loop response across wide range of output capacitor ESR and capacitance values - eliminates need for custom compensation per design. |
| 100% duty cycle in Boost Burst Mode | Maintains regulation during ultra-low load while sustaining full output voltage - essential for always-on systems with variable load profiles. |
| Very low dropout operation (99% duty cycle) | Enables buck regulation with minimal VIN–VOUT differential - improves efficiency in low-input scenarios like battery discharge. |
| Adjustable soft-start & tracking | Independent TRACK/SS1,2 and SS3 pins with internal 5µA charge current - supports controlled ramp-up and rail sequencing without external circuitry. |
| Triple independent current limit programming | ITH1/ITH2/ITH3 pins set per-channel peak current threshold - enables asymmetric current limits for mismatched output requirements. |
| EXTVCC switchover at 4.7V | Automatically selects most efficient bias source (VBIAS or auxiliary supply) - reduces power loss and heat generation in multi-rail systems. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management in engine control units where input drops to 2.5V during cranking. IC Role / Device Role / Timing Role: Triple-output controller regulating 5V microcontroller rail, 8.5V infotainment rail, and 10V boost rail for sensors. Use Value: Maintains all outputs in regulation during cold crank; 28µA IQ extends battery life between engine starts. | Use Scenario: Compact power solution for GPS/GSM modules operating from Li-ion or supercapacitor backup. IC Role / Device Role / Timing Role: Generates stable 3.3V, 5V, and 12V rails from single 3.6V–36V input using buck/buck/boost topology. Use Value: Eliminates need for separate boost IC; RSENSE/DCR flexibility reduces component count and board area. |
| Distributed DC Power Architecture | Industrial Control Panels |
Use Scenario: Centralized 24V bus powering multiple isolated subsystems with varying voltage needs. IC Role / Device Role / Timing Role: Provides local 5V logic, 12V analog, and 24V actuator rails with independent enable and soft-start. Use Value: Per-channel RUN control enables dynamic rail activation; phase-locking synchronizes switching to reduce conducted EMI. | Use Scenario: Powering PLC I/O modules in harsh environments requiring extended temperature operation. IC Role / Device Role / Timing Role: Regulates 3.3V FPGA core, 5V interface, and 24V fieldbus rails with AEC-Q100 Grade H reliability. Use Value: –40°C to +150°C operation ensures functionality in uncooled enclosures; exposed PGND pad aids thermal management. |
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 |
|---|---|---|---|
| LTC3859AHE#TRPBF | Same pinout and function but higher Burst Mode IQ (45µA vs 28µA); TSSOP package (θJA = 25°C/W) vs QFN. | Lower thermal performance; suitable for less thermally constrained designs with relaxed IQ requirements. | Select when board space permits TSSOP and 17µA higher IQ is acceptable for cost or availability reasons. |
| LTC3859HLE#TRPBF | Same UHF QFN package and IQ, but rated for –40°C to +125°C (vs +150°C); no AEC-Q100 qualification. | Not certified for automotive under-hood use; intended for industrial or commercial applications. | Choose for non-automotive designs where extended temperature range is unnecessary and cost sensitivity favors standard grade. |
Compared with LTC3859AHE#TRPBF and LTC3859HLE#TRPBF, the LTC3859ALHUHF#TRPBF delivers superior thermal performance (QFN θJA = 34.7°C/W), lowest IQ in Burst Mode, and full AEC-Q100 Grade H qualification - making it the optimal choice for thermally demanding, automotive-grade triple-rail power systems.
Availability
LTC3859ALHUHF#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-operated telematics, and distributed DC power architectures requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for LTC3859ALHUHF#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 DC/DC controllers optimized for automotive and industrial applications demanding ultra-low quiescent current, wide input range, and robust thermal performance.
FAQ
What is the minimum input voltage for LTC3859ALHUHF#TRPBF after startup?
The LTC3859ALHUHF#TRPBF can operate from an input supply as low as 2.5V after startup when biased from the boost converter output or another auxiliary supply - enabling reliable regulation during automotive cold-crank events where battery voltage dips below 6V.
Does LTC3859ALHUHF#TRPBF support phase synchronization with external clocks?
Yes, the LTC3859ALHUHF#TRPBF supports phase synchronization via the PLLIN/MODE pin, which accepts an external clock signal to align the rising edge of TG1 with the external clock's rising edge - reducing system-level EMI through synchronized switching across multiple regulators.
How does the OPTI-LOOP compensation in LTC3859ALHUHF#TRPBF benefit design flexibility?
The OPTI-LOOP compensation in LTC3859ALHUHF#TRPBF allows the transient response to be optimized across a wide range of output capacitance and ESR values - eliminating the need for custom compensation networks and enabling reuse of the same controller across diverse output capacitor selections without stability risk.
Can LTC3859ALHUHF#TRPBF drive both buck and boost outputs simultaneously?
Yes, the LTC3859ALHUHF#TRPBF is designed to drive all three outputs (two buck, one boost) simultaneously, with independent feedback, current sensing, and soft-start control - supporting complex multi-rail power architectures such as 5V/8.5V/10V systems from a single 12V input.
What is the purpose of the EXTVCC pin on LTC3859ALHUHF#TRPBF?
The EXTVCC pin on LTC3859ALHUHF#TRPBF connects to an external 4.7V–14V supply to power the INTVCC LDO, bypassing the internal VBIAS-powered LDO when EXTVCC exceeds 4.7V - improving efficiency and reducing heat generation in systems with an available auxiliary bias rail.
LTC3859ALHUHF#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859ALHUHF#TRPBF FAQ
1.How can I place an order for LTC3859ALHUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALHUHF#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 LTC3859ALHUHF#TRPBF reliable?
The price and inventory of LTC3859ALHUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALHUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALHUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALHUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALHUHF#TRPBF?
LTC3859ALHUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALHUHF#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 LTC3859ALHUHF#TRPBF?
For technical support, including LTC3859ALHUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALHUHF#TRPBF requirements.
6.How does Aetrix verify that LTC3859ALHUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALHUHF#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 LTC3859ALHUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALHUHF#TRPBF?
All LTC3859ALHUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALHUHF#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 LTC3859ALHUHF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859ALHUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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