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Analog Devices Inc. LTC3859ALHFE
- Part No.:
- LTC3859ALHFE
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859ALHFE.pdf
- Description:
- IC POWER MANAGEMENT
- Quantity:
- Payment:
- Shipping:
Inventory:2,026
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Product details
Overview
LTC3859ALHFE 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, 4.5V–38V input range, and AEC-Q100 qualification for automotive start-stop systems.
For engineers reviewing the LTC3859ALHFE datasheet, LTC3859ALHFE pinout, LTC3859ALHFE application, or LTC3859ALHFE equivalent, key selection criteria include its triple-output topology, 0.8V/1.2V precision references, phase-lockable 75kHz–850kHz switching frequency, cold-crank operation down to 2.5V input, and 38-lead TSSOP package with exposed PGND pad.
Technical Context
The LTC3859ALHFE 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. It supports RSENSE or DCR current sensing, 100% duty cycle for boost synchronous MOSFETs even in Burst Mode, and OPTI-LOOP compensation for wide output capacitance/ESR optimization.
Its PLLIN/MODE pin enables dynamic light-load mode selection-Burst Mode (28µA IQ), pulse-skipping, or forced continuous conduction-while FREQ pin allows resistor-programmable fixed frequency (50kHz–900kHz) or external synchronization (75kHz–850kHz). The device integrates gate drivers with matched rise/fall times and precise dead-time control for TG/BG pairs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller with independent regulation per channel |
| Input Voltage Range | 4.5V–38V main bias; supports cold-crank down to 2.5V when biased from boost output or auxiliary supply |
| Quiescent Current | 28µA in Burst Mode with one channel active-enables extended battery runtime in always-on systems |
| Reference Voltages | 0.8V ±1.2% for buck outputs; 1.2V ±1.2% for boost output-ensures tight output regulation accuracy |
| Switching Frequency | Programmable 50kHz–900kHz or phase-lockable 75kHz–850kHz-supports EMI reduction and inductor size optimization |
| Output Voltage Range | Buck: 0.8V–24V; Boost: up to 60V-enables flexible rail generation for multi-voltage systems |
| Operating Temp | –40°C to +150°C junction-qualified per AEC-Q100 Grade H for under-hood automotive applications |
Pinout & Package
Package: 38-lead plastic TSSOP (FE package) with exposed PGND pad (Pin 39), rated θJA = 25°C/W. Must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2, RUN3 | Digital enable inputs per channel | Independent shutdown control; <1.17V (RUN1) or <1.20V (RUN2/3) disables respective controller |
| VFB1, VFB2, VFB3 | Feedback voltage inputs | Monitor regulated output via resistive divider; buck channels compare to 0.8V, boost to 1.2V reference |
| SENSE1+/–, SENSE2+/–, SENSE3+/– | Differential current sense inputs | Support RSENSE or DCR sensing; SENSE3+ supplies current to boost comparator; SENSE1,2– sources current when >INTVCC |
| TG1/TG2/TG3, BG1/BG2/BG3 | Top/bottom gate drivers | Drive N-MOSFET gates; TG swing = INTVCC superimposed on SW node; BG swing = GND to INTVCC |
| PLLIN/MODE | Light-load mode & sync input | Selects Burst Mode (ground), pulse-skipping (1.2V–INTVCC–1.3V), or forced CCM (INTVCC); accepts external clock for synchronization |
| PGOOD1 | Open-drain power-good indicator | Asserts low when VFB1 deviates >±10% from setpoint-enables system sequencing and fault reporting |
| OV3 | Boost overvoltage open-drain flag | Asserts low when VFB3 exceeds +10% of setpoint-provides dedicated boost rail fault detection |
| TRACK/SS1, TRACK/SS2, SS3 | Soft-start and tracking inputs | Internal 5µA pull-up; capacitor-to-ground sets ramp time; resistive divider enables output tracking during startup |
Key Features
| Feature | Design Value |
|---|---|
| 28µA Burst Mode IQ (one channel) | Extends battery life in automotive always-on modules without compromising startup capability at 2.5V input |
| Triple independent regulation | Enables simultaneous generation of multiple rails (e.g., 5V/8.5V/10V) with separate soft-start, tracking, and fault flags |
| 100% duty cycle boost operation | Maintains regulation during deep dropout conditions-even in Burst Mode-critical for cold-crank resilience |
| OPTI-LOOP compensation | Allows stable loop response across wide range of ceramic or polymer output capacitors without external tuning |
| AEC-Q100 Grade H qualification | Validated for –40°C to +150°C operation-meets automotive reliability requirements for engine control and ADAS power supplies |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management in vehicles with frequent engine stop/start cycles, requiring stable 5V, 8.5V, and variable 10V–VIN boost rail. IC Role / Device Role / Timing Role: Triple-output synchronous controller regulating critical ECUs and infotainment subsystems during 2.5V cold-crank events. Use Value: 28µA Burst Mode IQ preserves battery charge between starts; 100% boost duty cycle maintains regulation below 5V input. |
Use Scenario: Compact telematics unit powered by 12V lead-acid or Li-ion battery, needing isolated 5V, 8.5V, and programmable boost rail. IC Role / Device Role / Timing Role: Central DC/DC controller managing multi-rail power sequencing with tracking and soft-start for MCU, RF, and sensor subsystems. Use Value: Independent RUN pins enable staggered startup; PGOOD1 and OV3 provide discrete fault signaling for system-level diagnostics. |
| Distributed DC Power Systems | Multioutput Industrial Control |
Use Scenario: DIN-rail mounted industrial controller requiring 5V logic, 8.5V analog, and 10V–60V programmable boost for actuator drivers. IC Role / Device Role / Timing Role: High-efficiency triple-output controller supporting wide input (4.5V–38V) and high-voltage boost with RSENSE current sensing. Use Value: Phase-lockable frequency reduces EMI in dense layouts; EXTVCC input enables efficient biasing from local 5V rail. |
Use Scenario: Programmable logic controller (PLC) backplane supplying 5V I/O, 8.5V ADC reference, and 10V fieldbus interface with cold-swap tolerance. IC Role / Device Role / Timing Role: Robust synchronous controller with AEC-Q100 H-grade thermal rating and undervoltage lockout hysteresis (70mV). Use Value: –40°C to +150°C operation ensures reliability in uncooled enclosures; SGND separation minimizes noise coupling in mixed-signal designs. |
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 feature set but rated for –40°C to +125°C (Grade I); higher Burst Mode IQ (≈35µA with one channel) | Suitable for non-under-hood automotive or industrial applications where 150°C junction is not required | Select when cost sensitivity outweighs extreme temperature requirement and 125°C max junction suffices |
| LTC3859ALEFE#TRPBF | Same architecture but commercial grade (–40°C to +125°C); slightly higher feedback voltage drift (±0.8% vs ±0.6% over temp) | Targeted at consumer or telecom infrastructure where AEC-Q100 is unnecessary | Choose for lower-cost evaluation or non-automotive designs with standard industrial temperature range |
Compared with LTC3859AIFE#TRPBF and LTC3859ALEFE#TRPBF, the LTC3859ALHFE delivers guaranteed 150°C operation, tighter feedback tolerance, and lowest 28µA Burst Mode IQ-making it the only option qualified for under-hood automotive use with cold-crank resilience.
Availability
LTC3859ALHFE is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered telematics, and distributed DC power systems requiring stable component supply with AEC-Q100 compliance and extended temperature support.
Supply support for LTC3859ALHFE 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 cold-crank resilience, ultra-low quiescent current, and AEC-Q100 qualification.
FAQ
What is the minimum input voltage for LTC3859ALHFE during cold-crank conditions?
The LTC3859ALHFE maintains regulation with input as low as 2.5V when biased from the boost output or an auxiliary supply-enabling reliable operation during automotive cold-crank events where battery voltage dips below 5V. This capability is enabled by internal circuitry that allows the controller to operate below its nominal 4.5V–38V VBIAS range after initial startup, and is validated across the full –40°C to +150°C operating junction temperature range specified for the LTC3859ALHFE.
How does the LTC3859ALHFE achieve 28µA quiescent current?
The LTC3859ALHFE achieves 28µA quiescent current in Burst Mode with one channel active through optimized internal biasing, low-leakage CMOS design, and selective circuit shutdown-verified per datasheet Table on page 4 under "Sleep Mode (One Channel On, Buck)". This ultra-low IQ is maintained while preserving fast wake-up response and full functionality of the enabled channel's regulation loop, feedback comparators, and gate drivers-critical for automotive always-on applications.
Can LTC3859ALHFE drive both buck and boost channels simultaneously?
Yes, the LTC3859ALHFE supports concurrent operation of all three channels-two bucks and one boost-with independent RUN pin control, separate feedback loops (0.8V for bucks, 1.2V for boost), and dedicated fault indicators (PGOOD1 and OV3). Its architecture allows full regulation of each output regardless of load state, and the datasheet confirms stable operation with all channels enabled in both Burst Mode and forced continuous conduction modes.
What package type and thermal characteristics does LTC3859ALHFE use?
The LTC3859ALHFE uses a 38-lead plastic TSSOP (FE package) with exposed PGND pad (Pin 39), rated at θJA = 25°C/W. The exposed pad must be soldered to PCB copper for rated thermal performance and electrical grounding. This package supports the –40°C to +150°C junction temperature range required for AEC-Q100 Grade H qualification, and is distinct from the QFN (UHF) variant which has θJA = 34.7°C/W.
Does LTC3859ALHFE support external frequency synchronization?
Yes, the LTC3859ALHFE supports external synchronization via the PLLIN/MODE pin, accepting an external clock signal to phase-lock all three switching channels within a 75kHz–850kHz range. When synchronized, the rising edge of TG1 aligns with the rising edge of the external clock, enabling deterministic timing for EMI reduction and multi-phase power system coordination-confirmed in the Pin Functions section (page 11) and Electrical Characteristics (page 5).
LTC3859ALHFE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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-TSSOP-EP
LTC3859ALHFE FAQ
1.How can I place an order for LTC3859ALHFE through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALHFE 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 LTC3859ALHFE reliable?
The price and inventory of LTC3859ALHFE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALHFE is usually 5 days.
3.What payment methods are accepted for LTC3859ALHFE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALHFE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALHFE?
LTC3859ALHFE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALHFE 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 LTC3859ALHFE?
For technical support, including LTC3859ALHFE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALHFE requirements.
6.How does Aetrix verify that LTC3859ALHFE is sourced from the original manufacturer or authorized distributors?
All LTC3859ALHFE 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 LTC3859ALHFE meets industry standards.
7.What is the process for return or replacement of LTC3859ALHFE?
All LTC3859ALHFE units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALHFE, 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 LTC3859ALHFE part is unused and in its original packaging.
Return procedure for LTC3859ALHFE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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