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Analog Devices Inc. LTC3859AHUHF#PBF
- Part No.:
- LTC3859AHUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859AHUHF#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:156
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Product details
Overview
LTC3859AHUHF#PBF from Analog Devices is a high-performance triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, featuring 55μA no-load quiescent current, 0.8V/1.2V precision references for buck/boost outputs, and phase-lockable switching up to 850kHz - optimized for automotive start-stop and battery-powered digital systems requiring cold-crank operation down to 2.5V input.
For engineers reviewing the LTC3859AHUHF#PBF datasheet, LTC3859AHUHF#PBF pinout, LTC3859AHUHF#PBF application, or LTC3859AHUHF#PBF equivalent, key selection criteria include its triple-output topology with independent RUN control, OPTI-LOOP compensation for wide ESR/capacitance tolerance, Burst Mode® optimization for high-input boost regulation, and –40°C to 150°C junction temperature rating in the 38-pin 5mm × 7mm QFN package.
Technical Context
The LTC3859AHUHF#PBF implements three independent current-mode controllers: two buck channels with 0.8V reference and 99% dropout capability, and one boost channel with 1.2V reference and 100% duty cycle support even in Burst Mode®. Its constant-frequency architecture supports programmable fixed frequency (50–900kHz) or PLL synchronization (75–850kHz), with separate ITH pins enabling per-channel loop compensation and current limit setting.
It features dual gate drivers per channel (TG/BG) with matched rise/fall times (13–28ns), integrated INTVCC LDO (5.4V ±0.2V), EXTVCC switchover at 4.7V, and robust protection including PGOOD1 (±10% buck1 tolerance), OV3 (10% boost overvoltage), and undervoltage lockout (4.15V rising, 3.5V falling).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple synchronous controller - enables independent regulation of two step-down and one step-up outputs from single IC. |
| Input Voltage Range | 4.5V to 38V main bias; operates down to 2.5V after startup when biased from boost output - supports cold-crank automotive supply conditions. |
| Quiescent Current | 55μA in Sleep Mode (one channel active) - extends runtime in always-on battery systems without compromising regulation. |
| Reference Voltages | 0.8V ±1.2% for buck outputs; 1.2V ±1.2% for boost output - ensures tight output accuracy across temperature and load. |
| Switching Frequency | Programmable 50kHz–900kHz or PLL-synchronized 75kHz–850kHz - allows EMI optimization and inductor size reduction. |
| Operating Temperature | –40°C to +150°C junction - qualified for under-hood automotive and industrial high-temperature environments. |
| Package | 38-pin 5mm × 7mm QFN with exposed PGND pad - provides low thermal resistance (θJA = 34.7°C/W) and compact layout footprint. |
Pinout & Package
Package: 38-lead plastic QFN (5mm × 7mm), exposed PGND pad (Pin 39) requiring PCB soldering for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming input | Resistor-to-GND sets 50–900kHz fixed frequency; tie to GND/INTVCC for 350/535kHz defaults - enables EMI tuning without external clock. |
| PLLIN/MODE (Pin 2) | Sync input / light-load mode selector | Accepts external clock for phase-locking; selects Burst Mode® (ground), pulse-skipping (1.2–INTVCC−1.3V), or forced continuous (INTVCC) - controls efficiency vs ripple trade-off. |
| RUN1, RUN2, RUN3 (Pins 9,10,11) | Digital enable inputs per channel | Independent shutdown control: <1.17V (buck) or <1.20V (boost) disables respective regulator - enables sequenced power-up and dynamic output management. |
| VFB1, VFB2, VFB3 (Pins 36,14,6) | Feedback voltage inputs | Monitor output via resistor dividers; regulate to 0.8V (buck) or 1.2V (boost) - supports remote sensing and precise output setpoint control. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32/18/27, 29/21/25) | Top/bottom N-MOSFET gate drivers | Drive external high-side/low-side FETs with 1.0–2.5Ω on-resistance and <30ns transition times - ensures efficient synchronous rectification and minimal dead-time loss. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ compensation | Per-channel ITH pin enables stable loop response across wide range of output capacitor ESR (0.5–100mΩ) and capacitance (10–1000µF) - eliminates trial-and-error compensation design. |
| 100% duty cycle boost operation | Enables seamless regulation when VIN ≥ VOUT (e.g., 12V input → 12V output) without dropout - critical for backup power and hold-up applications. |
| Low IQ sleep mode | 55μA total supply current with one buck channel active - maintains system wakefulness while minimizing battery drain in standby. |
| Independent soft-start/tracking | TRACK/SS1,2 pins allow buck outputs to follow external rail; SS3 enables controlled ramp for boost - prevents inrush and enables power sequencing. |
| Robust fault signaling | PGOOD1 (buck1 only) and OV3 (boost overvoltage) open-drain outputs provide real-time status without additional monitoring circuitry. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Digital Devices |
|---|---|
Use Scenario: Power management in vehicles with engine stop/start cycles where battery voltage drops to 2.5V during cranking. IC Role / Device Role / Timing Role: Triple-output controller supplies 5V/8.5V microcontroller rails and 10V sensor bias, maintaining regulation through cold-crank transients. Use Value: 2.5V minimum operating input and 99% buck duty cycle prevent brownout during cranking; 55μA IQ extends battery life between starts. |
Use Scenario: Portable test equipment requiring isolated 3.3V logic, 12V analog, and 5V USB power from single Li-ion cell (2.7–4.2V). IC Role / Device Role / Timing Role: Buck1 generates 3.3V, buck2 generates 5V, boost3 generates 12V - all regulated independently with shared control logic. Use Value: Single-chip triple conversion reduces BOM count and PCB area; Burst Mode® delivers >85% efficiency at 1mA load for long idle periods. |
| Distributed DC Power Systems | Multioutput Industrial Controllers |
Use Scenario: Rack-mounted instrumentation needing 3.3V FPGA core, 12V ADC reference, and 24V actuator drive from 24V backplane. IC Role / Device Role / Timing Role: Dual buck channels deliver low-noise 3.3V/12V; boost channel steps up to 24V - all synchronized to common clock to minimize beat frequencies. Use Value: Phase-lockable 75–850kHz operation enables EMI filtering at known frequencies; EXTVCC input allows direct 24V bias for improved efficiency. |
Use Scenario: PLC I/O module requiring isolated 5V logic, 24V field power, and 15V analog supply in high-temperature cabinet (>85°C ambient). IC Role / Device Role / Timing Role: Controller manages three isolated DC/DC stages with independent RUN control for hot-swap capability and thermal derating. Use Value: –40°C to +150°C rating ensures reliability at elevated junction temperatures; PGOOD1 and OV3 signals feed into system watchdog logic. |
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 |
|---|---|---|---|
| LTC3859AEUHF#PBF | Same functionality and pinout; rated for –40°C to +125°C junction temperature (vs. +150°C for LTC3859AHUHF#PBF) | Suitable for commercial/industrial environments without extreme thermal stress | Select when ambient temperature remains below 85°C and full automotive-grade temp range is unnecessary. |
| LTC3859AIUHF#PBF | Identical electrical specs and package; guaranteed over –40°C to +125°C with production testing (vs. design-assured +150°C for H-grade) | Preferred for AEC-Q200-compliant designs requiring production-tested automotive qualification | Choose when formal automotive qualification documentation and test reports are required for certification. |
Compared with LTC3859AEUHF#PBF and LTC3859AIUHF#PBF, the LTC3859AHUHF#PBF offers extended high-temperature operation up to +150°C junction, enabling deployment in under-hood automotive locations or high-power-density industrial enclosures where thermal margins exceed 125°C - without sacrificing efficiency, feature set, or pin compatibility.
Availability
LTC3859AHUHF#PBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered portable instruments, and distributed industrial power supplies requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for LTC3859AHUHF#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3859A product line delivers high-efficiency, multi-output synchronous DC/DC controllers targeting demanding automotive and industrial applications where input voltage transients, thermal constraints, and ultra-low quiescent current are critical design parameters.
FAQ
What is the maximum input voltage the LTC3859AHUHF#PBF can handle?
The LTC3859AHUHF#PBF supports a main bias input (VBIAS) range of 4.5V to 38V. Its absolute maximum VBIAS rating is 40V, and boost switch node (SW3) withstands up to 70V. For reliable long-term operation, input voltage should remain within the 38V specified operating maximum - exceeding this risks permanent damage per Absolute Maximum Ratings.
Does the LTC3859AHUHF#PBF support synchronization to an external clock?
Yes, the LTC3859AHUHF#PBF supports external clock synchronization via the PLLIN/MODE pin (Pin 2). When an external clock signal is applied, the internal phase-locked loop aligns the rising edge of TG1 with the external clock's rising edge, enabling deterministic switching and EMI reduction. The synchronizable frequency range is 75kHz to 850kHz.
How does the LTC3859AHUHF#PBF achieve 2.5V minimum operating input?
The LTC3859AHUHF#PBF achieves 2.5V minimum operation by biasing its internal circuitry from the boost converter's output or an auxiliary supply - bypassing the main VBIAS input after startup. This allows regulation to continue during automotive cold-crank events where battery voltage dips below 4.5V, provided the boost output remains above 2.5V.
What is the purpose of the TRACK/SS1, TRACK/SS2, and SS3 pins on the LTC3859AHUHF#PBF?
TRACK/SS1 and TRACK/SS2 enable buck outputs to track an external voltage rail during startup, preventing sequencing violations; SS3 provides soft-start for the boost output. Each pin has an internal 1µA pull-up current source - connecting a capacitor to ground sets the ramp time, while resistive dividers allow precise tracking ratios. This eliminates need for external sequencing ICs.
Can the LTC3859AHUHF#PBF drive both buck and boost channels simultaneously?
Yes, the LTC3859AHUHF#PBF is designed for simultaneous triple-output operation. All three channels (buck1, buck2, boost3) operate independently with dedicated RUN pins, feedback inputs (VFB1/VFB2/VFB3), and current sense paths. The datasheet confirms 80–120μA Sleep Mode current with all three channels active - verifying concurrent regulation capability.
LTC3859AHUHF#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)
LTC3859AHUHF#PBF FAQ
1.How can I place an order for LTC3859AHUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AHUHF#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 LTC3859AHUHF#PBF reliable?
The price and inventory of LTC3859AHUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AHUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3859AHUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AHUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AHUHF#PBF?
LTC3859AHUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AHUHF#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 LTC3859AHUHF#PBF?
For technical support, including LTC3859AHUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AHUHF#PBF requirements.
6.How does Aetrix verify that LTC3859AHUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AHUHF#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 LTC3859AHUHF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3859AHUHF#PBF?
All LTC3859AHUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AHUHF#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 LTC3859AHUHF#PBF part is unused and in its original packaging.
Return procedure for LTC3859AHUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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