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Analog Devices Inc. LTC3859ALEUHF#TRPBF
- Part No.:
- LTC3859ALEUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859ALEUHF#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,174
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Product details
Overview
LTC3859ALEUHF#TRPBF 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 and boost outputs, and phase-lockable switching up to 850kHz. It supports cold-crank operation down to 2.5V input after startup and is used in automotive start-stop systems requiring multi-rail power sequencing.
For engineers reviewing the LTC3859ALEUHF#TRPBF datasheet, LTC3859ALEUHF#TRPBF pinout, LTC3859ALEUHF#TRPBF application, or LTC3859ALEUHF#TRPBF equivalent, key selection criteria include its triple-output topology, ultra-low IQ in sleep mode, AEC-Q100 qualification, and support for RSENSE or DCR current sensing across all channels.
Technical Context
The LTC3859ALEUHF#TRPBF implements three independent constant-frequency current-mode controllers: two buck stages with 0.8V reference and 99% max duty cycle, and one boost stage with 1.2V reference, 100% synchronous duty cycle capability, and up to 60V output. Its OPTI-LOOP compensation adapts transient response to varied output capacitance and ESR.
Control logic enables per-channel RUN pin enable/disable, selectable light-load modes (Burst, pulse-skipping, forced continuous) via PLLIN/MODE, and coordinated soft-start/tracking using dedicated TRACK/SS1–2 and SS3 pins. The device integrates gate drivers with matched rise/fall times (TG: 25/16ns; BG: 28/13ns) and low on-resistance (TG3/BG3: 1.2Ω/1.0Ω).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller - enables single-chip generation of multiple regulated rails including >VIN output. |
| Quiescent Current (IQ) | 28µA (one channel active, Burst Mode) - extends battery runtime in always-on automotive systems. |
| Input Voltage Range | 4.5V to 38V bias supply; operates down to 2.5V after startup when biased from boost output - supports cold-crank and wide automotive input transients. |
| Output Voltage References | 0.8V ±1.2mV (buck), 1.2V ±18mV (boost) - enables precise regulation of core logic (e.g., 1.2V FPGA I/O) and higher-voltage peripherals (e.g., 12V sensors). |
| Switching Frequency | 75kHz–850kHz phase-lockable; programmable 50kHz–900kHz via FREQ pin - allows EMI optimization and inductor size reduction. |
| Current Sensing | RSENSE or DCR sensing supported on all three channels - provides flexibility in loss vs. accuracy trade-offs for high-current applications. |
| Package & Temp Grade | 38-lead 5mm × 7mm QFN (UHF), –40°C to +125°C junction - meets automotive under-hood thermal requirements with exposed PGND pad for thermal management. |
Pinout & Package
38-lead (5mm × 7mm) plastic QFN package with exposed PGND pad (Pin 39), rated for –40°C to +125°C operating junction temperature and θJA = 34.7°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TG1, TG2, TG3 | Top-gate drive outputs | Drive N-channel high-side MOSFET gates with floating voltage swing; TG3 supports 100% duty cycle in boost mode. |
| BG1, BG2, BG3 | Bottom-gate drive outputs | Drive N-channel low-side MOSFET gates referenced to PGND; matched timing with TG for synchronous rectification. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– | Differential current sense inputs | Enable accurate peak-current-mode control; SENSE3+ sources current for boost channel sensing. |
| VFB1, VFB2, VFB3 | Feedback inputs | Monitor regulated output via resistor dividers; buck channels compare to 0.8V, boost to 1.2V internal reference. |
| RUN1, RUN2, RUN3 | Per-channel enable inputs | Independent digital control: <1.17V disables buck; <1.20V disables boost; all <0.7V shuts down entire IC. |
| PLLIN/MODE | Mode selection & sync input | Selects Burst Mode (ground), pulse-skipping (1.2V–INTVCC–1.3V), or forced continuous (INTVCC); accepts external clock for synchronization. |
| PGOOD1 | Power-good indicator | Open-drain output asserting low when VFB1 deviates >±10% from setpoint - enables system-level power sequencing validation. |
| OV3 | Boost overvoltage flag | Open-drain output asserting low when VFB3 exceeds +10% of setpoint - provides independent boost rail fault detection. |
| TRACK/SS1, TRACK/SS2, SS3 | Soft-start & tracking inputs | Internal 5µA pull-up enables capacitor-based ramp time; TRACK/SS1–2 allow buck outputs to track external supplies during startup. |
| PGND (Pin 39) | Power ground | Exposed thermal pad must be soldered to PCB plane - critical for thermal dissipation and driver return path integrity. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 qualified | Rated for automotive applications including start-stop and always-on systems, with guaranteed operation from –40°C to +125°C. |
| OPTI-LOOP compensation | Allows stable loop response across wide range of output capacitor types (ceramic, polymer, electrolytic) and ESR values without redesign. |
| 100% duty cycle support (boost) | Enables seamless transition to dropout operation in boost stage - maintains regulation even as input approaches output voltage. |
| Low shutdown IQ (10µA) | Minimizes standby power draw in battery-backed systems; achieved by fully disabling internal regulators and gate drivers. |
| Programmable light-load behavior | Three distinct modes (Burst, pulse-skipping, forced continuous) per channel optimize efficiency vs. ripple vs. EMI trade-offs. |
Applications
| Automotive Start-Stop Systems | Always-On Telematics Modules |
|---|---|
Use Scenario: Power management in vehicles with engine auto-shutdown at idle, requiring stable 5V/8.5V/10V rails during 2.5V cold-crank events. IC Role / Device Role / Timing Role: Triple-output controller generating buck-regulated microcontroller core voltage (5V), CAN transceiver supply (8.5V), and boost-regulated sensor interface (10V). Use Value: 28µA Burst Mode IQ extends battery life during extended stop periods; cold-crank tolerance prevents system reset below 2.5V input. |
Use Scenario: Always-on cellular/V2X modules drawing microampere standby current while maintaining GPS lock and network registration. IC Role / Device Role / Timing Role: Primary power controller delivering low-noise 1.2V FPGA core, 3.3V RF front-end, and 5V USB interface from 12V vehicle bus. Use Value: Independent RUN pin control enables selective shutdown of non-critical rails; PGOOD1/OV3 flags support autonomous fault recovery. |
| Distributed Battery-Powered Devices | Industrial Multi-Rail Power Supplies |
Use Scenario: Portable test equipment powered by Li-ion battery, requiring isolated 3.3V logic, 5V analog, and 12V actuator rails. IC Role / Device Role / Timing Role: Central synchronous controller managing buck conversion for logic/analog rails and boost for higher-voltage peripherals. Use Value: RSENSE/DCR flexibility accommodates high-current actuator drivers; 99% buck dropout ensures full battery utilization down to 2.8V. |
Use Scenario: Programmable logic controller (PLC) backplane supplying 24V field I/O, 5V CPU, and isolated 15V analog signal conditioning. IC Role / Device Role / Timing Role: High-efficiency triple-output controller replacing discrete DC/DC solutions to reduce board area and BOM count. Use Value: Phase-lockable frequency enables synchronized switching across multiple LTC3859AL units - reduces conducted EMI in dense industrial enclosures. |
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 functionality, but TSSOP-38 package and higher 48µA Burst Mode IQ (one channel on). | Preferred where manual assembly or legacy TSSOP footprint is required; less suitable for high-density automotive PCBs. | Select when thermal performance is secondary to assembly compatibility and cost. |
| LTC3859HIFE#TRPBF | Identical architecture but rated for –40°C to +150°C junction temperature; higher 56µA Burst Mode IQ (all channels on). | Required for under-hood applications exceeding +125°C ambient, such as near-engine ECU modules. | Choose when extended temperature grade is mandated by OEM thermal specifications. |
Compared with LTC3859ALEUHF#TRPBF, the TSSOP variant trades thermal performance for assembly flexibility, while the H-grade version adds temperature robustness at the cost of slightly higher light-load IQ - both retain identical control features and pin compatibility.
Availability
LTC3859ALEUHF#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, always-on telematics modules, and distributed battery-powered devices requiring stable component supply with AEC-Q100 compliance and long-term lifecycle support.
Supply support for LTC3859ALEUHF#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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, industrial automation, and automotive systems.
The LTC3859AL product line delivers triple-output synchronous controllers optimized for automotive power architectures requiring ultra-low quiescent current, cold-crank resilience, and flexible multi-rail sequencing - targeting next-generation ADAS and vehicle connectivity platforms.
FAQ
What is the minimum input voltage for LTC3859ALEUHF#TRPBF after startup?
The LTC3859ALEUHF#TRPBF 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 enables reliable regulation during automotive cold-crank events where battery voltage dips below 6V. Startup itself requires VBIAS ≥5V, but once running, the controller sustains operation down to 2.5V on the bias rail.
Does LTC3859ALEUHF#TRPBF support DCR current sensing on all three channels?
Yes, the LTC3859ALEUHF#TRPBF supports both RSENSE and DCR current sensing on all three channels (buck1, buck2, boost). The SENSE+ and SENSE– pins are designed to accommodate the voltage drop across either discrete sense resistors or the parasitic resistance of power inductors, with dedicated current sourcing/sinking capability on SENSE3+ for boost-stage DCR implementation.
How does the OPTI-LOOP compensation in LTC3859ALEUHF#TRPBF improve design flexibility?
The OPTI-LOOP compensation in LTC3859ALEUHF#TRPBF allows engineers to optimize transient response across diverse output capacitor types (e.g., ceramic, polymer, or electrolytic) and ESR values without changing external compensation components. By adjusting the ITH pin impedance, the loop bandwidth and phase margin adapt dynamically - reducing design iterations and enabling reuse of reference designs across different output filter configurations.
Can LTC3859ALEUHF#TRPBF synchronize all three channels to an external clock?
Yes, LTC3859ALEUHF#TRPBF synchronizes all three channels to a single external clock applied to the PLLIN/MODE pin. When an external clock is present, the phase-locked loop forces the rising edge of TG1 to align with the external clock's rising edge, and all regulators operate in forced continuous conduction mode - eliminating beat frequencies and simplifying EMI filtering in multi-controller systems.
What is the function of the OV3 pin on LTC3859ALEUHF#TRPBF?
The OV3 pin on LTC3859ALEUHF#TRPBF is an open-drain overvoltage indicator specific to the boost channel. It pulls low when VFB3 exceeds +10% of its regulated setpoint (e.g., >1.32V for a 1.2V reference) and goes high-impedance otherwise. This provides independent fault detection for the boost rail - enabling system-level safety monitoring without relying on PGOOD1, which only monitors buck1.
LTC3859ALEUHF#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)
LTC3859ALEUHF#TRPBF FAQ
1.How can I place an order for LTC3859ALEUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALEUHF#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 LTC3859ALEUHF#TRPBF reliable?
The price and inventory of LTC3859ALEUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALEUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALEUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALEUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALEUHF#TRPBF?
LTC3859ALEUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALEUHF#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 LTC3859ALEUHF#TRPBF?
For technical support, including LTC3859ALEUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALEUHF#TRPBF requirements.
6.How does Aetrix verify that LTC3859ALEUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALEUHF#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 LTC3859ALEUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALEUHF#TRPBF?
All LTC3859ALEUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALEUHF#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 LTC3859ALEUHF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859ALEUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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