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Analog Devices Inc. LTC3859AMPUHF#TRPBF
- Part No.:
- LTC3859AMPUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859AMPUHF#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,915
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Product details
Overview
LTC3859AMPUHF#TRPBF from Analog Devices is a triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFETs, featuring 55μA no-load quiescent current, 4.5V–38V input range, and 0.8V/1.2V precision references for buck and boost outputs - deployed in automotive start-stop systems requiring cold-crank regulation down to 2.5V.
For engineers reviewing the LTC3859AMPUHF#TRPBF datasheet, LTC3859AMPUHF#TRPBF pinout, LTC3859AMPUHF#TRPBF application, or LTC3859AMPUHF#TRPBF equivalent, this page delivers verified package mapping (38-pin 5mm × 7mm QFN), confirmed burst-mode optimization for boost stage, validated 99% buck dropout duty cycle, and real-world soft-start/tracking implementation details critical for multi-rail power sequencing.
Technical Context
The LTC3859AMPUHF#TRPBF integrates three independent current-mode controllers: two buck channels with 0.8V reference and one boost channel with 1.2V reference, each with dedicated ITH error amplifier outputs and differential SENSE+/- inputs supporting RSENSE or DCR sensing. Its OPTI-LOOP compensation enables stable loop response across wide output capacitance and ESR variations.
Phase-lockable oscillator supports 75kHz–850kHz synchronization via PLLIN/MODE pin, while FREQ pin allows resistor-programmable fixed frequency from 50kHz to 900kHz. The device features separate RUN pins per channel, PGOOD1 for buck1, OV3 for boost overvoltage detection, and dual bias options (VBIAS or EXTVCC) with automatic switchover at 4.7V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V main bias; operates down to 2.5V after startup when biased from boost output or auxiliary supply - enables cold-crank operation in automotive systems. |
| Quiescent Current (Sleep Mode) | 55μA with one buck or boost channel active - extends battery runtime in always-on applications without compromising regulation. |
| Buck Feedback Reference | 0.800V ±1.2mV (–40°C to 125°C) - ensures tight output voltage accuracy across temperature for core logic rails. |
| Boost Feedback Reference | 1.200V ±1.2mV (–40°C to 125°C) - supports precise high-voltage rail generation up to 60V with minimal drift. |
| Switching Frequency Range | 75kHz to 850kHz phase-lockable; 50kHz to 900kHz programmable via FREQ resistor - balances efficiency, size, and EMI in compact layouts. |
| Max Duty Cycle (Buck) | 99% - maintains regulation during deep dropout conditions (e.g., 12V input → 12V output), critical for automotive transients. |
| Gate Driver Strength | TG3/BG3 pull-up/pull-down: 1.2Ω/1.0Ω - drives high-side/lower-side N-MOSFETs efficiently with fast 12ns/13ns rise/fall times (CLOAD = 3300pF). |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed PGND pad (Pin 39), rated for –55°C to 150°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (Pin 39) | Driver Power Ground | Exposed thermal pad; must be soldered to PCB plane for thermal dissipation and low-impedance return path to bottom MOSFET sources. |
| RUN1, RUN2, RUN3 (Pins 9,10,11) | Digital Enable Inputs | Independent per-channel startup control; <1.17V (RUN1) or <1.20V (RUN2/3) disables respective regulator - enables staggered power sequencing. |
| VFB1, VFB2, VFB3 (Pins 36,14,6) | Feedback Inputs | High-impedance (±50nA) inputs sensing resistive divider outputs; regulate to 0.8V (buck) or 1.2V (boost) with ±1.2mV tolerance. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– (Pins 37,38,13,12,4,5) | Differential Current Sense | Support RSENSE or DCR sensing; SENSE3+ supplies current to comparator - enables accurate peak-current mode control in boost topology. |
| TG1/TG2/TG3, BG1/BG2/BG3 (Pins 32,36,27,29,33,25) | N-Channel Gate Drivers | High-current drivers (1.2Ω TG3 pull-up) with integrated dead-time control - eliminates external gate driver need for discrete MOSFETs. |
| PLLIN/MODE (Pin 2) | Sync Input / Light-Load Mode Select | Accepts external clock for synchronization; also selects Burst Mode (ground), pulse-skipping (1.2V–INTVCC–1.3V), or forced continuous (INTVCC) - optimizes efficiency vs ripple trade-off. |
Key Features
| Feature | Design Value |
|---|---|
| Triple Output Architecture | Dual buck + single boost controllers on single die - reduces BOM count and board space versus discrete solutions in multi-rail systems. |
| OPTI-LOOP Compensation | Single capacitor compensation per channel adapts to wide range of output caps (ceramic/tantalum) and ESR - simplifies stability tuning across design variants. |
| 100% Boost Duty Cycle in Burst Mode | Maintains regulation even when input voltage exceeds output (e.g., 14V VIN → 12V VOUT) - unique to LTC3859A vs prior LTC3859, critical for battery-fed boost rails. |
| Adjustable Soft-Start & Tracking | TRACK/SS1/2 pins enable voltage tracking between buck outputs; SS3 sets boost ramp rate - prevents inrush and ensures ordered power-up in FPGA/ASIC systems. |
| Low Shutdown IQ | 14μA shutdown current with all RUN pins low - meets ultra-low standby requirements in automotive infotainment and telematics modules. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Digital Devices |
|---|---|
Use Scenario: Vehicle electrical system sustains microcontroller, sensors, and CAN transceivers during engine cranking where battery drops to 2.5V. IC Role / Device Role / Timing Role: LTC3859AMPUHF#TRPBF regulates three independent rails (e.g., 5V, 8.5V, 10V) while maintaining regulation through cold-crank transients. Use Value: 99% buck duty cycle and 2.5V minimum operating voltage ensure uninterrupted power delivery during cranking events. |
Use Scenario: Portable medical monitor with LCD, ADC, and wireless MCU requires isolated, low-noise 3.3V, 5V, and 12V rails from single Li-ion cell. IC Role / Device Role / Timing Role: LTC3859AMPUHF#TRPBF implements dual buck (3.3V/5V) and boost (12V) conversion with independent soft-start sequencing. Use Value: 55μA sleep IQ extends battery life; adjustable TRACK/SS pins prevent back-powering and ensure safe power-up order. |
| Distributed DC Power Systems | Multioutput Buck-Boost Applications |
Use Scenario: Industrial IoT gateway with Ethernet PHY, PoE interface, and ARM SoC needs tightly regulated 1.8V, 3.3V, and 5V from 24V bus. IC Role / Device Role / Timing Role: LTC3859AMPUHF#TRPBF replaces three discrete controllers, using VBIAS from 24V bus and generating all rails with shared thermal management. Use Value: Single-package integration reduces layout complexity; phase-lockable frequency minimizes beat frequencies in dense multi-converter environments. |
Use Scenario: Test equipment requiring programmable output (e.g., 3.3V–24V buck, 5V–60V boost) from variable 5–36V input source. IC Role / Device Role / Timing Role: LTC3859AMPUHF#TRPBF configures buck channels for wide-range step-down and boost channel for high-voltage step-up with independent feedback. Use Value: 60V max boost output and 0.8V–24V buck range support flexible lab-grade power supply designs without redesign. |
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#TRPBF | Same architecture and pinout; rated for –40°C to 125°C (vs –55°C to 150°C for LTC3859AMPUHF#TRPBF) | Suitable for commercial/industrial ambient environments; not qualified for extended military or aerospace thermal profiles | Select LTC3859AMPUHF#TRPBF when operation below –40°C or above 125°C junction is required. |
| LTC3859AHUHF#TRPBF | Same architecture and pinout; rated for –40°C to 150°C (vs –55°C to 150°C); lacks extended low-temp qualification | Validated for high-temp automotive under-hood use but not for cryogenic storage or operation | Choose LTC3859AMPUHF#TRPBF for applications requiring guaranteed functionality at –55°C (e.g., avionics, space-qualified subsystems). |
Compared with LTC3859AEUHF#TRPBF and LTC3859AHUHF#TRPBF, the LTC3859AMPUHF#TRPBF uniquely supports full operation from –55°C to 150°C junction temperature - enabling deployment in extreme-environment systems where thermal margin and low-temperature startup are non-negotiable.
Availability
LTC3859AMPUHF#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered digital devices, and distributed DC power systems requiring stable component supply across extended temperature ranges.
Supply support for LTC3859AMPUHF#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, multi-output synchronous DC/DC controllers optimized for automotive and industrial applications demanding wide input range, ultra-low quiescent current, and robust transient performance.
FAQ
What is the operating temperature range of the LTC3859AMPUHF#TRPBF?
The LTC3859AMPUHF#TRPBF is specified for a junction temperature range of –55°C to 150°C, making it suitable for extreme-environment applications such as aerospace, defense, and under-hood automotive systems where standard industrial-grade parts fail. This rating is verified per Analog Devices' MP-grade qualification testing protocol.
How does the LTC3859AMPUHF#TRPBF achieve 55μA quiescent current?
The LTC3859AMPUHF#TRPBF achieves 55μA no-load IQ by dynamically disabling internal circuitry - including gate drivers, oscillators, and error amplifiers - in Sleep Mode while retaining regulation capability. This is confirmed in Electrical Characteristics Table (IQ = 55μA, one channel on, –40°C to 125°C).
Can the LTC3859AMPUHF#TRPBF drive both buck and boost channels simultaneously?
Yes, the LTC3859AMPUHF#TRPBF supports concurrent operation of all three channels: two buck and one boost. Electrical Characteristics confirm Sleep Mode IQ rises to 80–120μA with all three channels active, and Figure 12's typical application circuit demonstrates simultaneous 5V, 8.5V, and 10V output regulation.
What is the purpose of the EXTVCC pin on the LTC3859AMPUHF#TRPBF?
The EXTVCC pin on the LTC3859AMPUHF#TRPBF provides an alternative bias path to the internal INTVCC LDO, engaging automatically when voltage exceeds 4.7V. This reduces power loss and heat generation when an efficient auxiliary supply (e.g., pre-regulated 5V or 8.5V) is available - validated in Electrical Characteristics (VLDOEXT, VEXTVCC switchover).
Does the LTC3859AMPUHF#TRPBF support phase synchronization across all three channels?
Yes, the LTC3859AMPUHF#TRPBF supports full phase synchronization: the PLLIN/MODE pin accepts an external clock that locks the rising edge of TG1 to the external clock, and the internal oscillator propagates synchronized timing to all three channels. This is documented in the Oscillator and PLL section (fSYNC = 75kHz–850kHz).
LTC3859AMPUHF#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:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859AMPUHF#TRPBF FAQ
1.How can I place an order for LTC3859AMPUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AMPUHF#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 LTC3859AMPUHF#TRPBF reliable?
The price and inventory of LTC3859AMPUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AMPUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859AMPUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AMPUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AMPUHF#TRPBF?
LTC3859AMPUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AMPUHF#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 LTC3859AMPUHF#TRPBF?
For technical support, including LTC3859AMPUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AMPUHF#TRPBF requirements.
6.How does Aetrix verify that LTC3859AMPUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AMPUHF#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 LTC3859AMPUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859AMPUHF#TRPBF?
All LTC3859AMPUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AMPUHF#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 LTC3859AMPUHF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859AMPUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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