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Analog Devices Inc. LTC3859ALHUHF#WTRPBF
- Part No.:
- LTC3859ALHUHF#WTRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALHUHF#WTRPBF.pdf
- Description:
- 3X OUT, BUCK/BUCK/BOOST SYNC CNT
- Quantity:
- Payment:
- Shipping:
Inventory:1,965
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Product details
Overview
LTC3859ALHUHF#WTRPBF 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 (down to 2.5V post-startup). It enables cold-crank automotive power systems requiring regulated 5V, 8.5V, and adaptive 10V/variable boost outputs.
For engineers reviewing the LTC3859ALHUHF#WTRPBF datasheet, LTC3859ALHUHF#WTRPBF pinout, LTC3859ALHUHF#WTRPBF application, or LTC3859ALHUHF#WTRPBF equivalent, key selection criteria include its AEC-Q100 qualification, 38-lead 5mm × 7mm QFN package with exposed PGND pad, phase-lockable 75kHz–850kHz switching frequency, and selectable light-load modes (Burst, pulse-skipping, continuous).
Technical Context
The LTC3859ALHUHF#WTRPBF 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. Its OPTI-LOOP compensation supports wide output capacitance/ESR ranges, while RSENSE or DCR sensing enables flexible current monitoring.
It integrates three high-current gate drivers (TG/BG) with sub-30ns transition times, programmable soft-start/tracking, and dedicated overvoltage indicators (PGOOD1, OV3). The device supports EXTVCC switchover (4.5V–4.7V threshold) and operates up to 150°C junction temperature, meeting automotive thermal requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V main bias; supports down to 2.5V after startup via boost output or auxiliary supply |
| Buck Output Reference | 0.8V ±1.2mV (0°C–85°C), enabling precise 5V/8.5V regulation with low dropout (99% duty cycle) |
| Boost Output Reference | 1.2V ±18mV (0°C–85°C), supporting up to 60V output with 100% synchronous duty cycle in Burst Mode |
| Quiescent Current | 28µA in Sleep Mode (one buck channel active), extending battery runtime in always-on systems |
| Switching Frequency | Programmable 50kHz–900kHz or phase-lockable 75kHz–850kHz, enabling EMI optimization and compact magnetics |
| Operating Temperature | –40°C to +150°C junction, qualified per AEC-Q100 for under-hood automotive applications |
| Package | 38-lead 5mm × 7mm QFN with exposed PGND pad (θJA = 34.7°C/W), ensuring thermal reliability |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed PGND pad (Pin 39), requiring soldering to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency control | Resistor-to-GND sets 50kHz–900kHz; tied to GND/INTVCC for fixed 350kHz/535kHz |
| PLLIN/MODE (Pin 2) | Light-load mode & sync input | GND = Burst Mode (28µA IQ); INTVCC = forced continuous; external clock = phase-locked sync |
| RUN1/RUN2/RUN3 (Pins 9,10,11) | Per-channel enable/disable | <1.17V (buck) or <1.20V (boost) disables channel; all <0.7V shuts down entire IC |
| VFB1/VFB2/VFB3 (Pins 36,14,6) | Feedback voltage inputs | Monitor output via resistor divider; regulate to 0.8V (buck) or 1.2V (boost) |
| TG1/TG2/TG3 (Pins 32,18,27) | Top-gate N-MOS drivers | Drive high-side FETs with floating output referenced to SW node; 1.2Ω pull-down resistance |
| BG1/BG2/BG3 (Pins 29,21,25) | Bottom-gate N-MOS drivers | Drive low-side FETs from PGND to INTVCC; 1.1Ω pull-down resistance |
| PGND (Pin 39) | Power ground reference | Exposed pad must be soldered to PCB plane for thermal dissipation and driver return path |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output architecture | Dual buck + single boost controllers enable compact multi-rail power supplies without discrete regulators |
| OPTI-LOOP compensation | Allows stable loop response across wide range of ceramic capacitor values and ESR, reducing design iterations |
| 100% duty cycle boost operation | Maintains regulation during deep dropout (e.g., cold crank to 2.5V) without diode conduction loss |
| AEC-Q100 qualification | Validated for automotive temperature range (–40°C to +150°C) and reliability requirements |
| Low shutdown IQ | 10µA shutdown current minimizes battery drain in parked-vehicle scenarios |
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 infotainment, 8.5V ADAS sensor, and adaptive boost rail during cold-crank transients. Use Value: 99% buck duty cycle and 100% boost duty cycle prevent output collapse below 2.5V input. | Use Scenario: Long-life GPS tracking unit powered by Li-ion battery with ultra-low standby consumption. IC Role / Device Role / Timing Role: Primary power controller delivering regulated rails while minimizing no-load current draw. Use Value: 28µA Burst Mode IQ extends operational lifetime between charges in always-on monitoring mode. |
| Distributed DC Power Architecture | Industrial Control HMI |
Use Scenario: Central 24V bus powering multiple isolated subsystems with varying voltage needs. IC Role / Device Role / Timing Role: Local DC/DC controller generating 5V logic, 8.5V display backlight, and 10V analog sensor supply from shared rail. Use Value: Independent channel enable/disable (RUN pins) allows dynamic rail sequencing and power gating. | Use Scenario: Human-machine interface panel requiring clean, sequenced 5V, 8.5V, and variable boost for LCD bias. IC Role / Device Role / Timing Role: Synchronous buck/boost controller with TRACK/SS pins enabling controlled power-up ramp. Use Value: Adjustable soft-start and voltage tracking prevent inrush current and ensure safe system boot sequence. |
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#WTRPBF | Same pinout and features but higher Burst Mode IQ (35µA vs 28µA at one channel on) | Less suitable for ultra-low-power battery backup; identical thermal rating (–40°C to +150°C) | Select when cost sensitivity outweighs 7µA IQ advantage and full AEC-Q100 compliance is retained |
| LTC3859ALIUHF#WTRPBF | Identical functionality and IQ, but rated for –40°C to +125°C (not +150°C) | Not qualified for under-hood placement; suitable for cabin electronics only | Choose for non-under-hood automotive applications where lower temperature grade reduces cost |
Compared with LTC3859AHUHF#WTRPBF and LTC3859ALIUHF#WTRPBF, the LTC3859ALHUHF#WTRPBF delivers the lowest quiescent current in Burst Mode while maintaining full AEC-Q100 qualification for 150°C operation-critical for engine compartment power systems requiring both ultra-low standby draw and high-temperature resilience.
Availability
LTC3859ALHUHF#WTRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered telematics, and distributed DC power architectures requiring stable component supply with AEC-Q100 assurance and extended temperature support.
Supply support for LTC3859ALHUHF#WTRPBF 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 series belongs to Analog Devices' Power by Linear™ portfolio, designed specifically for high-efficiency, multi-rail DC/DC conversion in demanding automotive and industrial environments where low IQ, wide input range, and robust thermal performance are essential.
FAQ
What is the minimum input voltage required for LTC3859ALHUHF#WTRPBF to operate after startup?
The LTC3859ALHUHF#WTRPBF 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 is critical for automotive cold-crank conditions where battery voltage drops transiently below 5V. The device maintains regulation on all three outputs during such events due to its 99% buck and 100% boost duty cycle support.
How does the PLLIN/MODE pin configure light-load behavior in LTC3859ALHUHF#WTRPBF?
The PLLIN/MODE pin on the LTC3859ALHUHF#WTRPBF selects light-load operating mode: grounding the pin enables Burst Mode (28µA IQ), tying it to INTVCC forces continuous conduction, and applying 1.2V–(INTVCC–1.3V) selects pulse-skipping. When used for synchronization, an external clock applied to this pin locks the TG1 rising edge to the clock's rising edge while enforcing forced continuous mode across all channels.
Is LTC3859ALHUHF#WTRPBF pin-compatible with earlier LTC3859 variants?
Yes, the LTC3859ALHUHF#WTRPBF is fully pin-compatible with the LTC3859 and LTC3859A, sharing identical pinout, package dimensions, and functional interface. The primary enhancement is reduced Burst Mode quiescent current (28µA vs higher values in predecessors), achieved without layout or schematic changes-enabling drop-in replacement in existing designs targeting lower standby power.
What thermal considerations apply to the exposed pad (Pin 39) of LTC3859ALHUHF#WTRPBF?
The exposed pad (Pin 39) of the LTC3859ALHUHF#WTRPBF is PGND and must be soldered to a PCB thermal pad connected to a solid ground plane. With θJA = 34.7°C/W in the 5mm × 7mm QFN package, proper pad soldering and copper area are essential to maintain junction temperature ≤150°C under full load. Thermal vias to internal ground layers are recommended to enhance heat dissipation in high-power automotive applications.
Can LTC3859ALHUHF#WTRPBF support output voltage tracking during startup?
Yes, the LTC3859ALHUHF#WTRPBF supports voltage tracking via TRACK/SS1 and TRACK/SS2 pins for buck channels and SS3 for the boost channel. By connecting a resistor divider from a master supply to TRACK/SS1/2, the buck outputs ramp proportionally to that supply. For the boost channel, SS3 accepts a soft-start ramp voltage to control output rise time. Internal 5µA pull-up current sources enable simple RC-based timing networks for controlled sequencing.
LTC3859ALHUHF#WTRPBF 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:
- 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#WTRPBF FAQ
1.How can I place an order for LTC3859ALHUHF#WTRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALHUHF#WTRPBF 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#WTRPBF reliable?
The price and inventory of LTC3859ALHUHF#WTRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALHUHF#WTRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALHUHF#WTRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALHUHF#WTRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALHUHF#WTRPBF?
LTC3859ALHUHF#WTRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALHUHF#WTRPBF 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#WTRPBF?
For technical support, including LTC3859ALHUHF#WTRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALHUHF#WTRPBF requirements.
6.How does Aetrix verify that LTC3859ALHUHF#WTRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALHUHF#WTRPBF 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#WTRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALHUHF#WTRPBF?
All LTC3859ALHUHF#WTRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALHUHF#WTRPBF, 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#WTRPBF part is unused and in its original packaging.
Return procedure for LTC3859ALHUHF#WTRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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