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Analog Devices Inc. LTC3859EFE#PBF
- Part No.:
- LTC3859EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859EFE#PBF.pdf
- Description:
- IC REG CTRLR MULT TOP 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,648
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Product details
Overview
LTC3859EFE#PBF from Analog Devices is a triple-output synchronous DC/DC controller supporting buck/buck/boost topologies with independent control of each channel. It delivers 5V/5A and 8.5V/3A from buck stages and a regulated boost output up to 60V, operating from 4.5V–38V input (or down to 2.5V post-startup). Its 55μA no-load quiescent current, 0.8V/1.2V precision references, and phase-lockable 75kHz–850kHz switching frequency make it suitable for automotive start-stop and battery-powered digital systems.
For engineers reviewing the LTC3859EFE#PBF datasheet, LTC3859EFE#PBF pinout, LTC3859EFE#PBF application, or LTC3859EFE#PBF equivalent, key selection criteria include its triple-channel current-mode architecture, RSENSE/DCR sensing flexibility, OPTI-LOOP compensation, independent TRACK/SS pins for soft-start/tracking, and support for Burst Mode®, pulse-skipping, or forced continuous operation at light loads.
Technical Context
The LTC3859EFE#PBF integrates three independent current-mode controllers: two 180° out-of-phase buck regulators (Channels 1 & 2) and one boost regulator (Channel 3) synchronized in-phase with Channel 1. Each channel features dedicated ITH error amplifier outputs, VFB feedback inputs, SENSE± differential current sense inputs, and RUN enable pins.
Its constant-frequency architecture supports programmable fixed frequency (50kHz–900kHz) via FREQ pin resistor or external synchronization (75kHz–850kHz) via PLLIN/MODE. The device uses separate 0.8V (buck) and 1.2V (boost) internal references, with ±10% PGOOD1 monitoring on VFB1 and OV3 overvoltage flag on VFB3.
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 (bias), or 2.5V post-startup when biased from boost output - supports cold-crank automotive operation. |
| Output Voltage Accuracy | ±1.5% over temperature for buck (0.8V ref), ±1.5% for boost (1.2V ref) - ensures tight regulation across load/temperature. |
| Quiescent Current | 55μA (one channel active, sleep mode) - extends battery runtime in always-on systems. |
| Switching Frequency | 75kHz to 850kHz (phase-lockable) or 50kHz to 900kHz (programmable) - balances efficiency, size, and EMI. |
| Current Sensing | RSENSE or DCR - allows flexible, accurate inductor current measurement with minimal power loss. |
| Duty Cycle Range | Up to 99% for buck (low-dropout), 100% for boost synchronous MOSFET - maintains regulation under extreme VIN/VOUT ratios. |
Pinout & Package
Package: 38-pin plastic TSSOP (5mm × 7mm footprint, exposed PGND pad). Thermal resistance θJA = 25°C/W. Exposed pad (Pin 39) must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VFB1, VFB2, VFB3 | Feedback Input | Resistive divider output connection point; regulates to 0.8V (buck) or 1.2V (boost). |
| SENSE1+/–, SENSE2+/–, SENSE3+/– | Differential Current Sense | Measures inductor current via RSENSE or DCR; enables cycle-by-cycle current limiting and foldback. |
| TG1, TG2, TG3 / BG1, BG2, BG3 | Gate Drivers | High-current N-MOSFET drivers: TG drives high-side (buck) or low-side (boost); BG drives low-side (buck) or high-side (boost). |
| SW1, SW2, SW3 | Switch Node | Connection to inductor; carries high di/dt switching waveforms - requires tight layout and Kelvin routing. |
| RUN1, RUN2, RUN3 | Enable Control | Digital per-channel shutdown: <1.20V disables boost/buck; <0.7V shuts down entire IC (IQ = 14μA). |
| TRACK/SS1, TRACK/SS2, SS3 | Soft-Start/Tracking | Capacitor-based ramp control for controlled voltage rise; TRACK/SS1/2 allow output tracking of external supplies. |
| PGOOD1, OV3 | Status Outputs | Open-drain indicators: PGOOD1 signals VFB1 within ±10%; OV3 asserts when VFB3 exceeds +10% setpoint. |
| PLLIN/MODE | Mode Selection & Sync | Selects Burst Mode® (ground), pulse-skipping (1.2V–INTVCC−1.3V), or forced CCM (INTVCC); accepts external clock for synchronization. |
| FREQ | Oscillator Programming | Resistor-to-GND sets frequency (50kHz–900kHz); INTVCC = 535kHz, GND = 350kHz - enables precise EMI tuning. |
| VBIAS, EXTVCC, INTVCC | Power Inputs/Outputs | VBIAS powers internal LDO (4.5V–38V); EXTVCC >4.7V bypasses VBIAS LDO; INTVCC = 5.4V ±4% powers all circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent current-mode controllers | Enables simultaneous regulation of three distinct output rails with separate loop compensation and sequencing. |
| OPTI-LOOP™ compensation | Allows stable loop response across wide range of output capacitor ESR and capacitance values without redesign. |
| Low IQ sleep mode (55μA) | Extends battery life in portable and automotive always-on applications without sacrificing startup capability. |
| 100% duty cycle boost gate drive | Maintains regulation even when VIN approaches VOUT, critical for high-efficiency boost in low-input scenarios. |
| Independent TRACK/SS pins | Supports coordinated power-up sequencing and voltage tracking between multiple rails or external supplies. |
| Current foldback protection | Reduces MOSFET conduction losses during short-circuit events, improving thermal reliability and system robustness. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Digital Devices |
|---|---|
Use Scenario: Power management in vehicles with engine auto-stop/restart, requiring stable 5V and 8.5V rails during cold-crank (VIN dips to 2.5V). IC Role / Device Role / Timing Role: Triple-output controller maintaining regulation across wide input transients while minimizing standby current draw. Use Value: Enables uninterrupted operation of infotainment, ADAS sensors, and CAN transceivers during cranking events. |
Use Scenario: Portable test equipment or handheld instrumentation requiring isolated 5V, 8.5V, and 10V+ rails from single Li-ion or 12V battery. IC Role / Device Role / Timing Role: Primary DC/DC controller managing multi-rail power sequencing and efficiency optimization across load states. Use Value: Delivers >90% efficiency at 1A–5A loads while extending runtime via 55μA sleep IQ and Burst Mode® at light loads. |
| Distributed DC Power Systems | Industrial Embedded Controllers |
Use Scenario: Centralized 24V/48V bus powering multiple downstream modules needing 5V logic, 8.5V analog, and 10V–60V actuator rails. IC Role / Device Role / Timing Role: High-density, thermally efficient controller enabling compact board layout with shared thermal path via exposed PGND pad. Use Value: Reduces component count vs. discrete controllers and eliminates need for external bias supplies via integrated INTVCC LDO. |
Use Scenario: Programmable logic controller (PLC) backplane supplying FPGA core (5V), I/O interface (8.5V), and fieldbus transceiver (12V–24V) rails. IC Role / Device Role / Timing Role: Robust, temperature-stable controller with –40°C to 125°C operation and ±10% PGOOD monitoring. Use Value: Ensures deterministic power-up timing and fault reporting via independent RUN pins and open-drain status outputs. |
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#PBF | Same silicon, QFN package (5mm × 7mm), θJA = 34°C/W vs. TSSOP's 25°C/W; identical electrical specs and pinout. | Better thermal performance in space-constrained layouts; requires different PCB land pattern and reflow profile. | Select for higher power density or improved thermal dissipation where board area permits QFN mounting. |
| LTC3859EFE#TRPBF | Identical TSSOP package and specs; supplied in 2,000-unit tape-and-reel vs. tube-packaged #PBF variant. | Optimized for automated SMT assembly; same performance and qualification level as #PBF. | Choose for high-volume production requiring reel-fed placement; no design or validation impact. |
Compared with LTC3859EFE#PBF, the IUHF variant offers superior thermal resistance in a smaller footprint but requires QFN-specific layout and assembly, while the #TRPBF variant provides identical performance in a production-optimized packaging format without any circuit or thermal trade-offs.
Availability
LTC3859EFE#PBF 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, long-term lifecycle support, and guaranteed traceability.
Supply support for LTC3859EFE#PBF 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, designed specifically for demanding automotive, battery, and industrial power applications requiring multi-rail regulation and robust transient response.
FAQ
What is the minimum input voltage required for LTC3859EFE#PBF startup?
The LTC3859EFE#PBF requires a minimum 5V on VBIAS to initiate startup. Once running, it can sustain operation down to 2.5V input if biased from the boost output or another auxiliary supply - a key feature for automotive cold-crank resilience. This behavior is confirmed in the Absolute Maximum Ratings and Applications sections of the Rev. C datasheet.
Does LTC3859EFE#PBF support phase interleaving between its two buck channels?
Yes, LTC3859EFE#PBF inherently operates its two buck channels (1 and 2) 180° out of phase, reducing input ripple current and allowing smaller input capacitors. This interleaving is hardwired in the controller architecture and does not require external synchronization signals or configuration.
Can LTC3859EFE#PBF regulate its boost output above 60V?
No - the LTC3859EFE#PBF's boost output is limited to a maximum of 60V, as specified in the Features section and validated by the ABSOLUTE MAXIMUM RATINGS for BOOST3 (–0.3V to 76V) and SW3 (–5V to 70V), which constrain practical regulation to ≤60V for safety margin and reliability.
How does the OPTI-LOOP™ compensation in LTC3859EFE#PBF simplify design?
OPTI-LOOP™ compensation in LTC3859EFE#PBF allows stable closed-loop response across a wide range of output capacitor types and ESR values without changing external compensation components. This reduces design iterations and qualification time when selecting ceramic, polymer, or electrolytic output capacitors.
What is the function of the OV3 pin on LTC3859EFE#PBF?
The OV3 pin on LTC3859EFE#PBF is an open-drain overvoltage indicator for the boost channel only. It pulls low when VFB3 is within regulation (≤110% of setpoint) and goes high-impedance when VFB3 exceeds +10% - providing fail-safe monitoring for high-voltage boost rails in safety-critical applications.
LTC3859EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LTC3859EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859EFE#PBF 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#PBF reliable?
The price and inventory of LTC3859EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859EFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3859EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859EFE#PBF?
LTC3859EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859EFE#PBF 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#PBF?
For technical support, including LTC3859EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859EFE#PBF requirements.
6.How does Aetrix verify that LTC3859EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3859EFE#PBF 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#PBF meets industry standards.
7.What is the process for return or replacement of LTC3859EFE#PBF?
All LTC3859EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859EFE#PBF, 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#PBF part is unused and in its original packaging.
Return procedure for LTC3859EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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