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Analog Devices Inc. LTC3859EFE#TRPBF
- Part No.:
- LTC3859EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859EFE#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOP 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,205
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Product details
Overview
LTC3859EFE#TRPBF from Analog Devices is a triple-output synchronous DC/DC controller supporting buck/buck/boost topologies with all-N-channel MOSFET drive, 4.5V–38V input range, 0.8V/0.8V/1.2V precision references, and 55μA no-load quiescent current - enabling long runtime in automotive always-on and battery-powered digital systems.
For engineers reviewing the LTC3859EFE#TRPBF datasheet, LTC3859EFE#TRPBF pinout, LTC3859EFE#TRPBF application, or LTC3859EFE#TRPBF equivalent, key selection considerations include phase-lockable 75kHz–850kHz operation, independent TRACK/SS control per channel, RSENSE or DCR current sensing, and cold-crank regulation down to 2.5V input.
Technical Context
The LTC3859EFE#TRPBF implements three independent constant-frequency current-mode controllers: two 180°-out-of-phase bucks (Channels 1 & 2) and one boost (Channel 3) synchronized to Channel 1. Each channel features dedicated ITH error amplifier output, VFB feedback input, and SENSE± differential current sense interface.
It supports multiple light-load modes via PLLIN/MODE pin selection (Burst Mode®, pulse-skipping, or forced continuous), employs OPTI-LOOP compensation for wide ESR/capacitance stability, and integrates dual LDOs - one biased from VBIAS (4.5V–38V) and another switchover-capable from EXTVCC (≥4.7V) - both regulating INTVCC to 5.4V ±0.2V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost - enables dual regulated low-voltage rails plus high-voltage boost rail from single input. |
| Input Voltage Range | 4.5V to 38V (VBIAS); after startup, operates down to 2.5V when biased from boost output or auxiliary supply. |
| Feedback References | 0.800V ±12mV (buck Ch1/Ch2), 1.200V ±18mV (boost Ch3) - ensures tight output regulation across temperature. |
| Quiescent Current | 55μA (one channel active, sleep mode) - extends battery life in always-on systems without sacrificing start-up capability. |
| Switching Frequency | Programmable 50kHz–900kHz or phase-lockable 75kHz–850kHz - allows EMI optimization and inductor size reduction. |
| Current Sensing | RSENSE or DCR sensing per channel - supports high-efficiency, low-heat designs with minimal external components. |
| Duty Cycle Limits | 99% max for buck (dropout), 100% for boost synchronous MOSFET - maintains regulation during extreme input transients. |
Pinout & Package
Package: 38-pin 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 |
|---|---|---|
| VFB1, VFB2, VFB3 | Feedback Input | Resistive divider node for buck1/buck2/boost output voltage regulation; references 0.8V/0.8V/1.2V internal references. |
| SENSE1+, SENSE1−, etc. | Differential Current Sense | Measures MOSFET current via RSENSE or inductor DCR; sets peak current limit via ITH voltage. |
| TG1, TG2, TG3 / BG1, BG2, BG3 | Gate Drivers | High-current N-MOSFET drivers: TG floats with SW node; BG referenced to PGND; 1.0–1.2Ω on-resistance ensures fast switching. |
| TRACK/SS1, TRACK/SS2, SS3 | Soft-Start & Tracking Control | Capacitor-based ramp for controlled voltage rise; TRACK pins enable output voltage sequencing with external supplies. |
| PLLIN/MODE | Light-Load Mode & Sync Input | Selects Burst Mode® (ground), pulse-skipping (1.2V–INTVCC−1.3V), or forced CCM (INTVCC); accepts external clock for synchronization. |
| RUN1, RUN2, RUN3 | Channel Enable | Individual digital enable/disable: <1.20V shuts down buck/boost channel; all <0.7V enters 14μA shutdown. |
| PGOOD1, OV3 | Status Outputs | Open-drain PGOOD1 indicates buck1 regulation (±10%); OV3 signals boost overvoltage (>110% setpoint). |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP Compensation | Enables stable loop response across wide range of output capacitor ESR and capacitance values without redesign. |
| Independent Soft-Start/Tracking | Three dedicated pins (TRACK/SS1, TRACK/SS2, SS3) allow staggered, sequenced, or externally tracked power-up of all outputs. |
| Cold-Crank Operation | Maintains regulation on buck outputs even when input drops to 2.5V - critical for automotive start-stop and cranking events. |
| Low-IQ Sleep Mode | 55μA IQ with one channel active preserves battery energy while retaining fast wake-up capability and output hold-up. |
| Flexible Current Sensing | Supports both discrete RSENSE and lossless DCR sensing - reduces BOM cost and conduction losses in high-current designs. |
| Robust Gate Drive | Integrated 1.0–1.2Ω pull-down/pull-up drivers with <30ns transition times minimize switching losses and gate charge requirements. |
Applications
| Automotive Start-Stop Systems | Industrial Battery-Powered Instruments |
|---|---|
Use Scenario: Power management during engine cranking where battery voltage dips to 2.5V–6V for hundreds of milliseconds. IC Role / Device Role / Timing Role: Triple-output controller maintaining 5V/8.5V/10V rails for MCU, display, and sensor subsystems despite severe input sag. Use Value: Eliminates need for separate backup regulators or supercapacitors by sustaining regulation through cold-crank events. |
Use Scenario: Portable test equipment requiring isolated 3.3V logic, 12V analog, and 24V actuator rails from a single Li-ion pack (3.0V–4.2V). IC Role / Device Role / Timing Role: Buck/buck/boost controller generating three independent, tightly regulated outputs with ultra-low quiescent current. Use Value: 55μA sleep IQ extends operational runtime >2× versus comparable controllers, enabling multi-day field use. |
| Distributed DC Power Architectures | Always-On Telematics Modules |
Use Scenario: Central 24V bus powering multiple downstream point-of-load converters in telecom or factory automation racks. IC Role / Device Role / Timing Role: Primary controller delivering 5V (digital), 12V (interface), and 48V (PoE midspan) rails with phase interleaving to reduce input ripple. Use Value: 180° phase shift between buck channels cuts input capacitor RMS current by ~30%, lowering thermal stress and size. |
Use Scenario: Cellular/V2X telematics unit that must remain powered and monitor CAN bus during vehicle ignition-off periods. IC Role / Device Role / Timing Role: Always-on power controller supplying 3.3V MCU core, 1.8V RF modem, and 5V GPS LNA from 12V vehicle battery. Use Value: 14μA shutdown IQ prevents battery drain over weeks; RUN pin sequencing enables graceful firmware suspend/resume. |
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 silicon, QFN-38 package (5mm × 7mm) with lower θJA (34°C/W vs 25°C/W), higher thermal performance at elevated ambient. | Better suited for high-power-density or convection-cooled industrial designs where board space is constrained. | Select when thermal margin is critical and PCB layout supports exposed-pad soldering; identical functionality and pinout. |
| LTC3873EDHC#TRPBF | Dual-output buck controller only (no boost), 600kHz max frequency, 85μA IQ, 32-pin DFN package. | Lacks third output and cold-crank capability below 4.5V; cannot replace LTC3859EFE#TRPBF in boost-dependent applications. | Consider only if system requires only two regulated rails and operates strictly above 4.5V input; not a functional substitute. |
Compared with LTC3859IUHF#TRPBF, the LTC3859EFE#TRPBF offers identical electrical performance in a TSSOP package optimized for manual assembly and thermal relief via larger pad area; compared with LTC3873EDHC#TRPBF, it delivers essential third-output flexibility and sub-4.5V operation required for automotive and battery-critical designs.
Availability
LTC3859EFE#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, long-term lifecycle support, and guaranteed traceability.
Supply support for LTC3859EFE#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 LTC3859 belongs to Analog Devices' Power by Linear™ family of high-efficiency, low-quiescent-current DC/DC controllers - engineered specifically for demanding automotive, battery, and always-on applications where input voltage resilience and standby power efficiency are critical.
FAQ
What is the minimum input voltage required for LTC3859EFE#TRPBF startup?
The LTC3859EFE#TRPBF requires ≥5V on VBIAS to initiate startup. Once running, it can sustain operation with input as low as 2.5V when biased from its own boost output or an auxiliary supply - a key feature for automotive cold-crank scenarios. Startup voltage is enforced by internal UVLO circuitry with 4.5V typical rising threshold.
Does LTC3859EFE#TRPBF support phase interleaving between its two buck channels?
Yes, the LTC3859EFE#TRPBF inherently operates its two buck channels (Ch1 and Ch2) 180° out of phase. This interleaving reduces input capacitor RMS current and output voltage ripple without requiring external timing components or synchronization signals - simplifying design and improving power density.
Can LTC3859EFE#TRPBF regulate its boost output above 60V?
No. The LTC3859EFE#TRPBF's boost output is limited to a maximum of 60V, as specified in the Absolute Maximum Ratings (BOOST3 voltage ≤76V, SW3 ≤70V) and confirmed in the Applications section. Exceeding 60V risks violating safe operating area limits and invalidating protection features like OV3 detection.
How does the OPTI-LOOP compensation in LTC3859EFE#TRPBF simplify design?
The OPTI-LOOP architecture in LTC3859EFE#TRPBF dynamically adjusts compensation based on output capacitor ESR and capacitance, allowing stable loop response across diverse ceramic, polymer, or electrolytic capacitor types - eliminating iterative compensation tuning and reducing design cycle time for varying output filter configurations.
What is the function of the EXTVCC pin on LTC3859EFE#TRPBF?
The EXTVCC pin on LTC3859EFE#TRPBF connects to an external 4.7V–14V supply to power the INTVCC LDO, bypassing the VBIAS-regulated path. This improves efficiency and thermal performance when a clean, low-noise auxiliary rail is available - especially beneficial in systems with pre-regulated intermediate voltages.
LTC3859EFE#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
LTC3859EFE#TRPBF FAQ
1.How can I place an order for LTC3859EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859EFE#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 LTC3859EFE#TRPBF reliable?
The price and inventory of LTC3859EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859EFE#TRPBF?
LTC3859EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859EFE#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 LTC3859EFE#TRPBF?
For technical support, including LTC3859EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859EFE#TRPBF requirements.
6.How does Aetrix verify that LTC3859EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859EFE#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 LTC3859EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859EFE#TRPBF?
All LTC3859EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859EFE#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 LTC3859EFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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