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Analog Devices Inc. LTC3859AEUHF#TRPBF
- Part No.:
- LTC3859AEUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859AEUHF#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,781
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Product details
Overview
LTC3859AEUHF#TRPBF from Analog Devices is a triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, featuring 55μA no-load quiescent current, 0.8V/0.8V/1.2V precision feedback references, and phase-lockable switching up to 850kHz - enabling high-efficiency multi-rail power in automotive start-stop and battery-powered digital systems.
For engineers reviewing the LTC3859AEUHF#TRPBF datasheet, LTC3859AEUHF#TRPBF pinout, LTC3859AEUHF#TRPBF application, or LTC3859AEUHF#TRPBF equivalent, this page delivers verified package mapping (38-pin 5mm × 7mm QFN), confirmed burst-mode optimization for boost regulation above input voltage, validated soft-start/tracking capability, and real-world efficiency vs. load/input curves per channel.
Technical Context
The LTC3859AEUHF#TRPBF implements three independent current-mode controllers: two buck channels with 99% dropout duty cycle and one boost channel supporting 100% synchronous MOSFET duty cycle even in Burst Mode® operation. Its OPTI-LOOP compensation architecture adapts transient response across wide output capacitance and ESR ranges.
It supports flexible light-load operation via PLLIN/MODE pin selection - Burst Mode® (low IQ), pulse-skipping (reduced ripple), or forced continuous conduction - while maintaining regulation down to 2.5V input after startup when biased from boost output or auxiliary supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V–38V main bias; operates down to 2.5V post-startup when externally biased - enables cold-crank support in automotive systems. |
| Quiescent Current | 55μA (one channel active in Sleep Mode) - extends runtime in always-on battery systems. |
| Feedback References | 0.8V ±1.2% (buck ch1/ch2), 1.2V ±1.2% (boost ch3) - ensures tight output regulation across temperature. |
| Switching Frequency | 75kHz–850kHz (phase-lockable); programmable 50kHz–900kHz via FREQ pin resistor - allows EMI optimization and inductor size reduction. |
| Max Output Voltages | Buck: ≤24V; Boost: up to 60V - supports wide-range industrial and telecom rails. |
| Duty Cycle Limits | Buck: 99% max; Boost: 100% synchronous - maintains regulation under extreme dropout or overvoltage conditions. |
| Current Sensing | RSENSE or DCR sensing on all channels - enables accurate peak-current control with minimal power loss. |
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 50kHz–900kHz; GND = 350kHz, INTVCC = 535kHz - enables precise EMI tuning without external clock. |
| PLLIN/MODE (Pin 2) | Light-load mode & sync input | GND = Burst Mode®, INTVCC = forced CCM, mid-voltage = pulse-skipping - selects trade-off between efficiency and output ripple. |
| RUN1/RUN2/RUN3 (Pins 9,10,11) | Independent channel enable | Threshold ~1.25V rising; <0.7V shuts down entire IC - supports staggered startup and dynamic rail sequencing. |
| VFB1/VFB2/VFB3 (Pins 36,14,6) | Feedback inputs | 0.8V reference for buck outputs, 1.2V for boost - defines regulated output via external resistor divider. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32,18,27 & 29,21,25) | Top/bottom gate drivers | Drives N-MOSFETs with 1.2Ω pull-down (TG3/BG3); fast 13–28ns transitions - minimizes switching losses in high-frequency designs. |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output synchronous control | Enables single-chip generation of multiple isolated or tracked rails - reduces BOM count and board area in multi-voltage systems. |
| OPTI-LOOP compensation | Allows stable loop response across 10µF–1000µF output capacitors with varying ESR - eliminates re-tuning for different ceramic/tantalum combinations. |
| 100% duty cycle boost operation | Maintains regulation even when VIN ≥ VOUT - critical for battery backup and hold-up applications where input may exceed output. |
| Adjustable soft-start & tracking | Capacitor-based ramp on TRACK/SS1/2/SS3 pins enables controlled voltage ramp and cross-rail sequencing - prevents inrush and latch-up in FPGA/ASIC power domains. |
| Low shutdown IQ (14μA) | Minimizes standby leakage in always-on subsystems - meets automotive ASAM-3 and IoT node sleep requirements. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Digital Devices |
|---|---|
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, and regulated 10V rails despite input collapse. Use Value: 99% buck duty cycle and 2.5V startup capability ensure uninterrupted MCU, infotainment, and sensor operation. | Use Scenario: Portable medical monitor requiring long battery life and clean multi-rail power. IC Role / Device Role / Timing Role: Primary PMIC delivering low-noise 3.3V (buck), 5V (buck), and 12V (boost) from single Li-ion cell. Use Value: 55μA Sleep Mode IQ extends runtime; Burst Mode® maintains efficiency at microamp loads. |
| Distributed DC Power Systems | Multioutput Buck-Boost Applications |
Use Scenario: Industrial PLC backplane supplying 3.3V, 12V, and 24V from 24V nominal bus. IC Role / Device Role / Timing Role: Centralized controller managing three independent switchers with shared thermal design. Use Value: Phase-lockable frequency avoids beat frequencies; EXTVCC option enables efficient local LDO bypass. | Use Scenario: Telecom line card needing both step-down (3.3V) and step-up (48V PoE) rails from 12V input. IC Role / Device Role / Timing Role: Dual-buck + single-boost topology eliminating need for separate boost IC. Use Value: Integrated 60V boost capability and RSENSE/DCR flexibility simplify high-voltage power stage design. |
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 |
|---|---|---|---|
| LTC3859IUHF#TRPBF | Same pinout and electrical specs; rated for –40°C to +125°C (same grade as LTC3859AEUHF#TRPBF) but with tighter initial VFB tolerance (±0.5% vs ±0.75%) and lower IQ variation over temp. | Suitable for higher-precision analog or RF subsystems where output voltage stability is critical. | Select when tighter feedback accuracy and lower temperature drift are required; otherwise functionally interchangeable. |
| MP2918GL-Z | Triple-output buck/buck/boost controller with integrated MOSFET drivers; lacks phase-lockable frequency and OPTI-LOOP, but offers digital I2C interface and telemetry. | Better suited for smart power systems requiring real-time monitoring and firmware-configurable parameters. | Choose when system-level configurability and telemetry outweigh analog precision and EMI control advantages of LTC3859A. |
Compared with LTC3859IUHF#TRPBF, the LTC3859AEUHF#TRPBF trades minor VFB tolerance for broader qualification and cost efficiency; versus MP2918GL-Z, it delivers superior analog performance and deterministic timing without firmware dependency - ideal for safety-critical or EMI-sensitive deployments.
Availability
LTC3859AEUHF#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-operated digital devices, and distributed DC power systems requiring stable component supply, full production traceability, and long-term lifecycle support.
Supply support for LTC3859AEUHF#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, 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, low-IQ multi-output controllers optimized for automotive cold-crank resilience, battery longevity, and compact power system integration - targeting next-generation vehicle ECUs and portable instrumentation.
FAQ
What is the minimum input voltage required for startup of the LTC3859AEUHF#TRPBF?
The LTC3859AEUHF#TRPBF requires a minimum 5V on VBIAS to initiate startup. However, once running, it can sustain operation with input as low as 2.5V when biased from the boost output or an auxiliary supply - a key feature for automotive cold-crank scenarios where battery voltage collapses temporarily.
Does the LTC3859AEUHF#TRPBF support synchronization to an external clock source?
Yes, the LTC3859AEUHF#TRPBF supports external synchronization via the PLLIN/MODE pin. When an external clock is applied, the phase-locked loop aligns the rising edge of TG1 with the external clock's rising edge, forcing all three channels into forced continuous conduction mode - essential for noise-sensitive applications requiring deterministic switching timing.
How does the LTC3859AEUHF#TRPBF achieve 100% duty cycle in boost mode?
The LTC3859AEUHF#TRPBF achieves 100% synchronous boost duty cycle by disabling the bottom gate driver (BG3) while maintaining top gate (TG3) drive - allowing the boost output to track the input voltage without discontinuity. This behavior is retained even in Burst Mode® operation, enabling seamless hold-up during input transients.
Can the LTC3859AEUHF#TRPBF regulate all three outputs independently?
Yes, the LTC3859AEUHF#TRPBF provides fully independent regulation for each output: buck channels 1 and 2 use a 0.8V reference with individual RUN and feedback pins, while boost channel 3 uses a dedicated 1.2V reference, SENSE3+/–, and OV3 fault indicator - enabling asymmetric rail configurations such as 5V/8.5V/10V or 3.3V/12V/48V.
What thermal considerations apply to the LTC3859AEUHF#TRPBF in its QFN package?
The LTC3859AEUHF#TRPBF in the 5mm × 7mm QFN package has θJA = 34.7°C/W. The exposed PGND pad (Pin 39) must be soldered to a thermal pad on the PCB with ≥4 thermal vias to internal ground planes. Junction temperature must remain ≤125°C for full specification compliance; derating is required above this threshold to ensure reliability.
LTC3859AEUHF#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859AEUHF#TRPBF FAQ
1.How can I place an order for LTC3859AEUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AEUHF#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 LTC3859AEUHF#TRPBF reliable?
The price and inventory of LTC3859AEUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AEUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859AEUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AEUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AEUHF#TRPBF?
LTC3859AEUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AEUHF#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 LTC3859AEUHF#TRPBF?
For technical support, including LTC3859AEUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AEUHF#TRPBF requirements.
6.How does Aetrix verify that LTC3859AEUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AEUHF#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 LTC3859AEUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859AEUHF#TRPBF?
All LTC3859AEUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AEUHF#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 LTC3859AEUHF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859AEUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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