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Analog Devices Inc. LTC3859ALEUHF#PBF
- Part No.:
- LTC3859ALEUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALEUHF#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,348
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Product details
Overview
LTC3859ALEUHF#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/boost outputs, and phase-lockable switching up to 850kHz - used in automotive start-stop systems requiring cold-crank operation down to 2.5V input.
For engineers reviewing the LTC3859ALEUHF#PBF datasheet, LTC3859ALEUHF#PBF pinout, LTC3859ALEUHF#PBF application, or LTC3859ALEUHF#PBF equivalent, key selection criteria include its triple-output topology, ultra-low IQ in sleep mode, AEC-Q100 qualification, and support for RSENSE or DCR current sensing across all channels.
Technical Context
The LTC3859ALEUHF#PBF implements constant-frequency current-mode control with independent ITH-based error amplifiers per channel, enabling precise current limit programming and transient response optimization via OPTI-LOOP compensation. Its architecture supports three distinct regulation loops: two buck converters (0.8V reference, ≤24V output) and one boost converter (1.2V reference, up to 60V output).
It features programmable operating modes - Burst Mode (28µA IQ), pulse-skipping, or forced continuous conduction - selected via the PLLIN/MODE pin, and integrates dedicated gate drivers (TG/BG) with sub-100ns transition times and 1.0–2.5Ω on-resistance for high-efficiency N-MOSFET switching across all three phases.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller - enables compact multi-rail power delivery without external controllers. |
| Quiescent Current (IQ) | 28µA in Burst Mode with one channel active - extends battery runtime in always-on automotive and portable systems. |
| Input Voltage Range | 4.5V to 38V bias range; operates down to 2.5V after startup when biased from boost output - supports cold-crank and wide-input industrial supplies. |
| Output Voltage References | 0.8V ±1% for buck channels; 1.2V ±1.2% for boost channel - ensures tight regulation across temperature and load for precision rail generation. |
| Switching Frequency | 75kHz–850kHz phase-lockable; 50kHz–900kHz programmable via resistor - allows EMI optimization and inductor size reduction. |
| Current Sensing | RSENSE or DCR sensing supported on all three channels - provides flexibility in loss vs. accuracy trade-offs for cost-sensitive designs. |
| Duty Cycle Range | Up to 99% for buck dropout; 100% for boost synchronous MOSFET - maintains regulation under extreme input/output ratios. |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed PGND pad (Pin 39), rated for –40°C to +125°C junction temperature (θJA = 34.7°C/W).
| 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) | Mode selection & sync input | Selects Burst/Pulse-Skipping/Continuous mode or accepts external clock for synchronization - critical for system-level timing coordination. |
| RUN1/RUN2/RUN3 (Pins 9,10,11) | Per-channel enable control | Logic-high >1.24V enables; <1.17V disables - allows independent sequencing and dynamic rail management. |
| VFB1/VFB2/VFB3 (Pins 36,14,6) | Feedback voltage inputs | Compare against 0.8V (buck) or 1.2V (boost) reference - defines regulated output voltage via external resistor divider. |
| 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 delays - ensures efficient synchronous rectification with minimal shoot-through risk. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 qualification | Rated for automotive applications including start-stop and always-on systems - meets reliability and temperature requirements for under-hood deployment. |
| 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 capability (boost) | Maintains regulation even when VIN ≥ VOUT - enables seamless transition between buck and boost operation in hybrid topologies. |
| Power good & overvoltage indicators | PGOOD1 (buck1) and OV3 (boost) open-drain outputs - provide system-level fault signaling without external monitoring circuitry. |
| Adjustable soft-start/tracking | Internal 5µA charge current into TRACK/SS pins - enables controlled ramp-up and rail sequencing with simple RC networks or external voltage followers. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management during engine cranking where battery voltage dips to 2.5V. IC Role / Device Role / Timing Role: Triple-output controller maintaining 5V/8.5V/10V rails while sustaining regulation through cold-crank events. Use Value: Eliminates need for separate LDOs or backup supplies; 28µA IQ preserves battery charge during extended idle periods. | Use Scenario: Compact telematics unit requiring isolated 5V, 8.5V, and variable boost rail from single 12V battery source. IC Role / Device Role / Timing Role: Central synchronous controller managing buck-buck-boost conversion with coordinated soft-start and tracking. Use Value: Reduces component count by 40% vs. discrete controllers; supports rapid wake-up from deep sleep via RUN pin control. |
| Distributed DC Power Systems | Industrial Control Panels |
Use Scenario: Multi-rail power distribution in DIN-rail mounted PLC modules with wide input range (9–36V DC). IC Role / Device Role / Timing Role: Primary regulator generating isolated logic, I/O, and analog supply rails from unregulated bus. Use Value: Phase-lockable frequency enables synchronized switching across multiple boards - reducing conducted EMI in dense enclosures. | Use Scenario: Human-machine interface panel requiring reliable 5V, 8.5V, and adjustable 10–60V boost for backlight or sensor excitation. IC Role / Device Role / Timing Role: High-voltage boost controller paired with dual bucks for mixed-signal subsystem powering. Use Value: 60V boost capability and 1.2V reference enable precise high-side sensing without external op-amps or level shifters. |
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#PBF | Same functionality but TSSOP-38 package; higher θJA (25°C/W); identical electrical specs and pinout. | Better thermal performance required in space-constrained QFN layouts; TSSOP preferred for manual assembly or rework. | Select LTC3859ALEUHF#PBF for automated SMT and thermal-limited PCBs; choose TSSOP variant if board real estate or hand-soldering is prioritized. |
| LTC3859HFE#PBF | Extended temperature grade (–40°C to +150°C); same QFN package and pinout; otherwise identical electrical behavior. | Required for under-hood automotive or high-ambient industrial environments exceeding 125°C junction. | Use LTC3859ALEUHF#PBF for standard automotive cabin or industrial ambient; upgrade to H-grade only when validated thermal margin is insufficient. |
Compared with LTC3859AIFE#PBF and LTC3859HFE#PBF, the LTC3859ALEUHF#PBF offers optimal thermal resistance (34.7°C/W) in the compact QFN footprint while maintaining full functional equivalence and AEC-Q100 compliance for mainstream automotive and industrial use cases.
Availability
LTC3859ALEUHF#PBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-operated telematics, and distributed DC power systems requiring stable component supply with long lifecycle assurance.
Supply support for LTC3859ALEUHF#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-output synchronous controllers optimized for automotive and industrial power systems demanding ultra-low quiescent current, wide input range, and robust cold-crank performance.
FAQ
What is the minimum input voltage for LTC3859ALEUHF#PBF after startup?
The LTC3859ALEUHF#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 - enabling sustained regulation during automotive cold-crank events where battery voltage collapses below 4.5V.
Does LTC3859ALEUHF#PBF support both RSENSE and DCR current sensing?
Yes, the LTC3859ALEUHF#PBF supports both RSENSE and DCR current sensing on all three channels (buck1, buck2, boost), with dedicated SENSE+ and SENSE– pins per channel and internal current sources configured for each method - providing design flexibility for efficiency versus cost trade-offs.
What is the purpose of the PLLIN/MODE pin on LTC3859ALEUHF#PBF?
The PLLIN/MODE pin on the LTC3859ALEUHF#PBF serves dual functions: it accepts an external clock for phase synchronization across multiple regulators, and selects light-load operating mode (Burst Mode, pulse-skipping, or forced continuous) - directly controlling quiescent current and ripple performance.
Is LTC3859ALEUHF#PBF qualified for automotive applications?
Yes, the LTC3859ALEUHF#PBF is AEC-Q100 qualified for automotive applications, rated for –40°C to +125°C operating junction temperature, and designed specifically for automotive always-on and start-stop systems - meeting stringent reliability and thermal requirements for under-dash deployment.
How does OPTI-LOOP compensation benefit designs using LTC3859ALEUHF#PBF?
OPTI-LOOP compensation in the LTC3859ALEUHF#PBF allows the transient response to be optimized across a wide range of output capacitance and ESR values - eliminating the need for custom loop compensation per capacitor type and simplifying design validation for varying load conditions and component tolerances.
LTC3859ALEUHF#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859ALEUHF#PBF FAQ
1.How can I place an order for LTC3859ALEUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALEUHF#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 LTC3859ALEUHF#PBF reliable?
The price and inventory of LTC3859ALEUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALEUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALEUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALEUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALEUHF#PBF?
LTC3859ALEUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALEUHF#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 LTC3859ALEUHF#PBF?
For technical support, including LTC3859ALEUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALEUHF#PBF requirements.
6.How does Aetrix verify that LTC3859ALEUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALEUHF#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 LTC3859ALEUHF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALEUHF#PBF?
All LTC3859ALEUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALEUHF#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 LTC3859ALEUHF#PBF part is unused and in its original packaging.
Return procedure for LTC3859ALEUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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