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Analog Devices Inc. LTC3859AMPUHF#PBF
- Part No.:
- LTC3859AMPUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859AMPUHF#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,746
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Product details
Overview
LTC3859AMPUHF#PBF from Analog Devices is a triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, featuring 55μA no-load quiescent current, 0.8V/1.2V precision references for buck/boost outputs, 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 LTC3859AMPUHF#PBF datasheet, LTC3859AMPUHF#PBF pinout, LTC3859AMPUHF#PBF application, or LTC3859AMPUHF#PBF equivalent, key selection criteria include its –55°C to 150°C operating range, 38-pin 5mm × 7mm QFN package, dual-buck-plus-boost topology support, and Burst Mode® optimization for battery runtime extension in always-on embedded power rails.
Technical Context
The LTC3859AMPUHF#PBF implements three independent current-mode controllers: two buck channels with 0.8V reference and 99% dropout duty cycle, and one boost channel with 1.2V reference and 100% synchronous duty cycle even in Burst Mode. Its OPTI-LOOP compensation supports wide output capacitance/ESR ranges.
It features programmable fixed-frequency (50–900kHz) or PLL-synchronized operation (75–850kHz), selectable light-load modes (Burst, pulse-skipping, forced continuous), and separate RUN pins per channel for independent enable/disable control - enabling flexible multi-rail sequencing in distributed power architectures.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input voltage range | 4.5V to 38V bias supply; operates down to 2.5V after startup when biased from boost output or auxiliary rail. |
| Buck output voltage range | 0.8V ≤ VOUT ≤ 24V, regulated by 0.8V ±1.2mV reference (–40°C to 125°C). |
| Boost output voltage range | Up to 60V, regulated by 1.2V ±1.2mV reference (–40°C to 125°C). |
| No-load quiescent current | 55μA (one channel active), enabling >1-year battery life in low-duty-cycle IoT sensors. |
| Switching frequency | Programmable 50kHz–900kHz or PLL-synchronized 75kHz–850kHz; supports noise-sensitive analog subsystems. |
| Operating temperature | –55°C to +150°C junction, qualified for extended-temperature automotive and industrial control applications. |
| Package | 38-pin 5mm × 7mm plastic QFN with exposed PGND pad for thermal and electrical integrity. |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed PGND pad (Pin 39), rated θJA = 34.7°C/W. Requires soldering of exposed pad to PCB ground plane for thermal performance and EMI reduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming | Resistor-to-GND sets 50–900kHz; tied to GND/INTVCC for fixed 350/535kHz operation. |
| PLLIN/MODE (Pin 2) | Sync input / light-load mode select | Accepts external clock for synchronization; selects Burst Mode (GND), pulse-skipping (1.2V–INTVCC–1.3V), or forced continuous (INTVCC). |
| RUN1, RUN2, RUN3 (Pins 9,10,11) | Per-channel enable control | Logic-high (>1.25V) enables respective controller; all <0.7V shuts down entire IC to 14μA. |
| VFB1, VFB2, VFB3 (Pins 36,14,6) | Feedback inputs | Monitor output via resistor divider; regulate to 0.8V (buck) or 1.2V (boost) with ±1.2mV accuracy. |
| TG1–3, BG1–3 (Pins 32,18,27 / 29,21,25) | N-MOSFET gate drivers | High-current floating (TG) and grounded (BG) drivers; TG1/2 pull-up 2.5Ω, TG3 pull-up 1.2Ω. |
| PGOOD1 (Pin 33) | Power-good indicator | Open-drain output asserts low when VFB1 deviates >±10% from setpoint - used for system sequencing. |
| OV3 (Pin 17) | Boost overvoltage flag | Open-drain output goes high-Z when VFB3 exceeds 110% of regulation point - enables external fault handling. |
| PGND (Pin 39) | Power ground return | Exposed thermal pad; must be soldered to PCB ground plane for thermal dissipation and low-noise gate drive return path. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent controllers | Two buck channels (0.8V ref) + one boost channel (1.2V ref) with fully separate RUN, ITH, and feedback paths. |
| Ultra-low IQ sleep mode | 55μA quiescent current with one channel active - extends battery life in always-on telematics modules. |
| OPTI-LOOP compensation | Allows stable loop response across wide output capacitor ESR (1mΩ–100mΩ) and capacitance (10μF–1000μF) ranges. |
| Cold-crank operation | Maintains regulation during automotive cranking events where input drops to 2.5V - critical for infotainment and ADAS ECUs. |
| 100% duty cycle boost | Enables seamless transition to pass-through mode when VIN ≥ VOUT - eliminates dropout in high-input scenarios. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management in engine control units during repeated 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 10V (actuator driver) rails from 12V battery. Use Value: Maintains regulation through cold crank via 2.5V startup capability and 99% buck duty cycle - prevents ECU brownout resets. | Use Scenario: Long-life GPS tracker powered by Li-ion battery with periodic wake-up and cellular transmission bursts. IC Role / Device Role / Timing Role: Generates low-noise 3.3V microcontroller rail and 5V RF transceiver rail while minimizing standby current. Use Value: 55μA sleep IQ extends 2000mAh battery life to >18 months at 10s/hour wake-up duty cycle. |
| Distributed DC Power Systems | Industrial Sensor Signal Conditioning |
Use Scenario: Multi-rail power for PLC I/O modules receiving 24V field bus input and requiring isolated 5V, 12V, and ±15V supplies. IC Role / Device Role / Timing Role: Primary non-isolated controller delivering 5V logic, 12V analog, and 24V interface rails from common 24V bus. Use Value: Dual-buck-plus-boost topology eliminates need for separate boost IC - reduces BOM count and board area by 30%. | Use Scenario: Precision analog front-end in vibration sensor node requiring ultra-low-noise 5V ADC reference and 15V op-amp supply. IC Role / Device Role / Timing Role: Generates clean 5V buck rail and 15V boost rail with independent soft-start and tracking for sequenced power-up. Use Value: Adjustable soft-start (via SS3/TRACK pins) prevents inrush current-induced voltage sag on shared 24V supply bus. |
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#PBF | Same architecture and pinout; rated for –40°C to 125°C (vs. –55°C to 150°C). | Suitable for commercial/industrial environments without extended temperature requirements. | Select when full –55°C rating is unnecessary and cost sensitivity favors standard grade. |
| LTC3859AHUHF#PBF | Same architecture and pinout; rated for –40°C to 150°C (vs. –55°C to 150°C); no –55°C qualification test data. | Valid for under-hood automotive use but not qualified for aerospace or extreme cold storage. | Select for high-temp-only applications where –55°C startup is not required. |
Compared with LTC3859AEUHF#PBF and LTC3859AHUHF#PBF, the LTC3859AMPUHF#PBF uniquely supports guaranteed operation at –55°C - essential for military-grade avionics, polar instrumentation, and deep-cold industrial automation where sub-zero startup reliability is non-negotiable.
Availability
LTC3859AMPUHF#PBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered telematics, and distributed DC power systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3859AMPUHF#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 LTC3859A product line delivers high-efficiency, multi-output synchronous DC/DC controllers optimized for demanding automotive and industrial power systems requiring cold-crank resilience, ultra-low quiescent current, and precise voltage regulation.
FAQ
What is the minimum input voltage required for startup of the LTC3859AMPUHF#PBF?
The LTC3859AMPUHF#PBF requires a minimum 5V on VBIAS to initiate startup. Once running, it can sustain operation with input as low as 2.5V when biased from the boost output or an auxiliary supply - enabling uninterrupted function during automotive cold-crank events where battery voltage dips below 5V.
How does the LTC3859AMPUHF#PBF achieve 55μA quiescent current?
The LTC3859AMPUHF#PBF achieves 55μA quiescent current by integrating optimized bias circuitry, low-leakage internal references, and adaptive gate drive logic that powers down unused channels. This specification is measured with one buck channel enabled and no load - verified across the full –55°C to 150°C operating range.
Can the LTC3859AMPUHF#PBF synchronize all three channels to an external clock?
Yes, the LTC3859AMPUHF#PBF synchronizes all three channels to a single external clock applied to the PLLIN/MODE pin. The phase-locked loop aligns the rising edge of TG1 to the external clock's rising edge, ensuring deterministic timing across buck/buck/boost outputs - critical for EMI reduction in noise-sensitive applications.
What is the purpose of the OV3 pin on the LTC3859AMPUHF#PBF?
The OV3 pin on the LTC3859AMPUHF#PBF is an open-drain overvoltage indicator for the boost channel. It transitions to high-impedance when VFB3 exceeds 110% of its regulated setpoint (1.2V), allowing external circuitry to detect and respond to boost output overvoltage faults - enhancing system safety in high-voltage industrial interfaces.
Does the LTC3859AMPUHF#PBF support adjustable soft-start for all three outputs?
Yes, the LTC3859AMPUHF#PBF supports independent soft-start: TRACK/SS1 and TRACK/SS2 pins enable tracking or soft-start for buck outputs, while SS3 controls soft-start for the boost output. Each uses an internal 1µA current source charging an external capacitor - providing precise ramp rate control without additional components.
LTC3859AMPUHF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN 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:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859AMPUHF#PBF FAQ
1.How can I place an order for LTC3859AMPUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AMPUHF#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 LTC3859AMPUHF#PBF reliable?
The price and inventory of LTC3859AMPUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AMPUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3859AMPUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AMPUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AMPUHF#PBF?
LTC3859AMPUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AMPUHF#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 LTC3859AMPUHF#PBF?
For technical support, including LTC3859AMPUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AMPUHF#PBF requirements.
6.How does Aetrix verify that LTC3859AMPUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AMPUHF#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 LTC3859AMPUHF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3859AMPUHF#PBF?
All LTC3859AMPUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AMPUHF#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 LTC3859AMPUHF#PBF part is unused and in its original packaging.
Return procedure for LTC3859AMPUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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