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Analog Devices Inc. LTC3859ALEFE#TRPBF
- Part No.:
- LTC3859ALEFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859ALEFE#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOP 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,375
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Product details
Overview
LTC3859ALEFE#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 respectively, and phase-lockable switching up to 850kHz - deployed in automotive start-stop systems requiring cold-crank operation down to 2.5V input.
For engineers reviewing the LTC3859ALEFE#TRPBF datasheet, LTC3859ALEFE#TRPBF pinout, LTC3859ALEFE#TRPBF application, or LTC3859ALEFE#TRPBF equivalent, key selection criteria include its triple-output topology, ultra-low IQ in sleep mode, AEC-Q100 qualification, wide 4.5V–38V bias input range, and support for RSENSE or DCR current sensing across all channels.
Technical Context
The LTC3859ALEFE#TRPBF integrates three independent current-mode controllers: two buck regulators with 0.8V reference and one boost regulator with 1.2V reference, each with dedicated ITH, SENSE+, SENSE−, VFB, RUN, and gate drive pins. Its OPTI-LOOP compensation enables stable loop response across broad output capacitance and ESR variations.
It supports multiple light-load operating modes via PLLIN/MODE pin selection - Burst Mode (28µA IQ), pulse-skipping, or forced continuous conduction - and features 100% duty cycle capability for the boost synchronous MOSFET even during Burst Mode, enabling seamless regulation during deep input voltage dips.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller - enables compact multi-rail power architecture without external drivers. |
| Quiescent Current (IQ) | 28µA with one channel active in Burst Mode - extends battery runtime in always-on automotive modules. |
| 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% for buck channels; 1.2V ±1% for boost channel - ensures tight output regulation across temperature and load. |
| 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 per channel - provides flexibility in efficiency vs. cost trade-offs for high-current applications. |
| Duty Cycle Limit | 99% for buck dropout; 100% for boost synchronous MOSFET - maintains regulation during extreme VIN/VOUT ratios. |
Pinout & Package
Package: 38-lead plastic TSSOP (FE package), 5mm × 7mm footprint, exposed PGND pad (Pin 39) requiring PCB soldering for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VBIAS | Main bias input supply | Accepts 4.5V–38V; powers internal circuitry; enables operation down to 2.5V post-startup when externally biased. |
| RUN1, RUN2, RUN3 | Digital enable inputs per channel | Independent shutdown control; <1.17V (buck) or <1.20V (boost) disables respective channel; all <0.7V enters full shutdown (10µA IQ). |
| TG1/TG2/TG3, BG1/BG2/BG3 | Top/bottom gate drivers | Drive N-MOSFETs; TG swing = INTVCC + SW node; BG swing = GND to INTVCC; low RDS(ON) (1.2Ω pull-down for TG3) minimizes switching losses. |
| SENSE1+/−, SENSE2+/−, SENSE3+/− | Differential current sense inputs | Support RSENSE or DCR sensing; SENSE3+ supplies current to comparator; SENSE1,2− sources current when >INTVCC - enables accurate peak-current mode control. |
| VFB1/VFB2/VFB3 | Feedback voltage inputs | Monitor output via resistor divider; regulate to 0.8V (buck) or 1.2V (boost); PGOOD1 monitors VFB1 only. |
| PLLIN/MODE | Mode selection & sync input | Selects Burst Mode (ground/floating), pulse-skipping (1.2V–INTVCC−1.3V), or forced CCM (INTVCC); accepts external clock for synchronization. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP compensation | Enables stable transient response across wide range of output capacitor values and ESR - eliminates need for iterative loop tuning in multi-capacitor designs. |
| 100% boost duty cycle in Burst Mode | Maintains regulation during deep input sags (e.g., automotive cold crank) without dropout - critical for safety-critical always-on rails. |
| AEC-Q100 qualification | Rated for −40°C to +125°C junction temperature (LTC3859ALE grade) - validated for automotive under-hood and infotainment applications. |
| Programmable soft-start/tracking | Internal 5µA charge current on TRACK/SS1,2 and SS3 pins - enables controlled ramp-up and sequencing of multiple output rails. |
| EXTVCC switchover | Automatically switches INTVCC supply from VBIAS to EXTVCC when >4.7V - improves efficiency by bypassing internal LDO during high-voltage auxiliary bias conditions. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics Units |
|---|---|
Use Scenario: Power management in engine control units during repeated engine stop/start cycles with input voltage collapsing to 2.5V. IC Role / Device Role / Timing Role: Triple-output controller generating 5V (ECU core), 8.5V (sensor bias), and regulated 10V (CAN transceiver) from 12V battery rail. Use Value: 28µA IQ preserves battery charge during extended idle; 99% buck duty cycle prevents dropout during cranking; AEC-Q100 ensures reliability. | Use Scenario: Compact telematics gateway powered by Li-ion battery with strict standby current budget. IC Role / Device Role / Timing Role: Generates isolated 3.3V (MCU), 5V (cellular modem), and boosted 12V (GPS antenna LNA) from single-cell 3.6V nominal input. Use Value: Ultra-low 28µA IQ extends weeks-long sleep mode; dual-buck + boost topology eliminates need for discrete boost IC; RSENSE sensing enables precise current limiting. |
| Distributed DC Power Architectures | Industrial IoT Edge Controllers |
Use Scenario: Central 24V bus powering multiple subsystems with independent voltage requirements and sequencing needs. IC Role / Device Role / Timing Role: Provides 5V (logic), 12V (actuator drivers), and 24V (fieldbus interface) rails with tracking soft-start to prevent inrush current conflicts. Use Value: TRACK/SS1,2 and SS3 pins enable coordinated ramp-up; phase-lockable frequency allows synchronized switching to reduce conducted EMI across distributed rails. | Use Scenario: DIN-rail mounted edge controller with 24V industrial supply and requirement for cold-swap tolerant power sequencing. IC Role / Device Role / Timing Role: Delivers 3.3V (ARM processor), 5V (USB peripherals), and 15V (isolated RS-485 transceivers) with independent RUN pin control per rail. Use Value: Individual RUN1/RUN2/RUN3 pins allow hot-plug sequencing and fault isolation; 38V max VBIAS withstands 48V surge events per IEC 61000-4-5. |
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 higher Burst Mode IQ (45µA typical with one channel on) and rated for −40°C to +125°C (same grade as LTC3859ALEFE#TRPBF). | Not AEC-Q100 qualified - suitable for industrial, not automotive, applications. | Select when AEC-Q100 is not required and slightly higher IQ is acceptable for cost-sensitive industrial designs. |
| LTC3859ALEUHF#TRPBF | Identical electrical specs and AEC-Q100 qualification, but in 38-lead 5mm × 7mm QFN (UHF) package with θJA = 34.7°C/W vs. TSSOP's 25°C/W. | Superior thermal performance in high-power density layouts; requires different PCB land pattern and reflow profile. | Select when board space is constrained and thermal dissipation demands lower junction-to-ambient resistance. |
Compared with LTC3859AIFE#TRPBF and LTC3859ALEUHF#TRPBF, the LTC3859ALEFE#TRPBF uniquely combines AEC-Q100 qualification, 28µA Burst Mode IQ, and TSSOP packaging - making it optimal for cost-sensitive, thermally moderate automotive applications where leaded assembly is preferred.
Availability
LTC3859ALEFE#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-operated telematics units, and distributed DC power architectures requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for LTC3859ALEFE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3859AL product line delivers high-efficiency, multi-output synchronous controllers optimized for automotive and industrial applications demanding ultra-low quiescent current, wide input voltage tolerance, and robust transient response.
FAQ
What is the minimum input voltage for LTC3859ALEFE#TRPBF after startup?
The LTC3859ALEFE#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 - enabling reliable regulation during automotive cold-crank events where battery voltage collapses below 6V. This behavior is distinct from its 4.5V minimum VBIAS requirement for initial startup.
Does LTC3859ALEFE#TRPBF support both RSENSE and DCR current sensing?
Yes, the LTC3859ALEFE#TRPBF supports both RSENSE and DCR current sensing on all three channels. SENSE1+/− and SENSE2+/− accept differential voltage across a sense resistor or inductor DCR network; SENSE3+/− uses a similar scheme for the boost channel, with SENSE3+ supplying current to the comparator - providing design flexibility for efficiency, cost, and thermal trade-offs.
How does the OPTI-LOOP compensation in LTC3859ALEFE#TRPBF improve design flexibility?
The OPTI-LOOP compensation in LTC3859ALEFE#TRPBF allows the transient response to be optimized across a wide range of output capacitance values and equivalent series resistance (ESR), eliminating the need for custom compensation networks when using ceramic, polymer, or electrolytic capacitors - significantly reducing design iteration time for multi-rail power systems.
Is LTC3859ALEFE#TRPBF pin-compatible with earlier LTC3859 variants?
Yes, the LTC3859ALEFE#TRPBF is fully pin-compatible with the LTC3859 and LTC3859A, sharing identical pinout, package dimensions, and functional mapping - enabling drop-in replacement in existing designs while delivering lower Burst Mode IQ (28µA vs. 45–55µA) and improved light-load efficiency.
What is the purpose of the EXTVCC pin on LTC3859ALEFE#TRPBF?
EXTVCC on the LTC3859ALEFE#TRPBF connects to an external supply (4.5V–14V) to power the INTVCC LDO, bypassing the internal VBIAS-powered LDO when EXTVCC exceeds 4.7V - improving overall system efficiency by reducing power loss in the bias regulator, especially in high-input-voltage or auxiliary-supply scenarios.
LTC3859ALEFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LTC3859ALEFE#TRPBF FAQ
1.How can I place an order for LTC3859ALEFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859ALEFE#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 LTC3859ALEFE#TRPBF reliable?
The price and inventory of LTC3859ALEFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859ALEFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859ALEFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859ALEFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859ALEFE#TRPBF?
LTC3859ALEFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859ALEFE#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 LTC3859ALEFE#TRPBF?
For technical support, including LTC3859ALEFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859ALEFE#TRPBF requirements.
6.How does Aetrix verify that LTC3859ALEFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859ALEFE#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 LTC3859ALEFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859ALEFE#TRPBF?
All LTC3859ALEFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859ALEFE#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 LTC3859ALEFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859ALEFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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