LTC3859AL

PRODUCTION

Triple Output, Buck/Buck/Boost Synchronous Controller with 28μA Burst Mode I_Q

Data Sheet (Rev. D) Product Selection Table

Part Models: 20
1ku List Price: Starting From $5.97

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Overview

Low Operating I_Q: 28μA (One Channel On)
Dual Buck Plus Single Boost Synchronous Controllers
Outputs Remain in Regulation Through Cold Crank Down to 2.5V
Wide Bias Input Voltage Range: 4.5V to 38V
Buck Output Voltage Range: 0.8V ≤ V_OUT ≤ 24V
Boost Output Voltage Up to 60V
R_SENSE or DCR Current Sensing
100% Duty Cycle for Boost Synchronous MOSFET Even in Burst Mode^® Operation
Phase-Lockable Frequency (75kHz to 850kHz)

Programmable Fixed Frequency (50kHz to 900kHz)
Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode Operation at Light Loads
Very Low Buck Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Low Shutdown I_Q: 10μA
Small 38-Lead 5mm × 7mm QFN and TSSOP Packages
AEC-Q100 Qualified for Automotive Applications

The LTC3859AL is a high performance triple output (buck/buck/boost) synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency of up to 850kHz. The LTC3859AL operates from a wide 4.5V to 38V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859AL can operate from an input supply as low as 2.5V after start-up.

The 28μA no-load quiescent current extends operating runtime in battery powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3859AL features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.

Compared to the LTC3859 and the LTC3859A, the LTC3859AL is fully pin-compatible, but with lower Burst Mode operation I_Q (28µA with one channel on).


	Quiescent Current (Burst Mode)	Notes
LTC3859AL	28μA-One channel on, Buck 38μA-All three channels on	Internal clamp on the INTVCC pin
LTC3859A	55μA-One channel on, Buck 80μA-All three channels on	Internal clamp on the INTVCC pin. For new designs, we recommend LTC3859AL
LTC3859	55μA-One channel on, Buck 80μA-All three channels on	For new designs, we recommend LTC3859AL

Applications

Automotive Always-On and Start-Stop Systems
Battery Operated Digital Devices
Distributed DC Power Systems
Multioutput Buck-Boost Applications

Part Models: 20
1ku List Price: Starting From $5.97

Documentation

Data Sheet 1

LTC3859AL: Triple Output, Buck/Buck/Boost Synchronous Controller with 28μA Burst Mode I_Q Data Sheet (Rev.D) 05/22/2023

User Guide 1

DC2122A - Demo Manual 03/07/2014

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC3859ALEFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALEFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALEUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALEUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALHFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALHFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALHUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALHUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALHUHF#WPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALHUHF#WTRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALIFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALIFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALIUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALIUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALIUHF#WPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALIUHF#WTRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALMPFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALMPFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALMPUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LTC3859ALMPUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

May 18, 2026 - 26_0072 Epoxy Change for Select TSSOP Products
		PCN26_0072_Form Material_Report Delta Qualification Matrix Qualification Results Summary
LTC3859ALEFE#PBF	PRODUCTION
LTC3859ALEFE#TRPBF	PRODUCTION
LTC3859ALHFE#PBF	PRODUCTION
LTC3859ALHFE#TRPBF	PRODUCTION
LTC3859ALIFE#PBF	PRODUCTION
LTC3859ALIFE#TRPBF	PRODUCTION
LTC3859ALMPFE#PBF	PRODUCTION
LTC3859ALMPFE#TRPBF	PRODUCTION
Apr 17, 2025 - 25_0043 Change of Gold to Copper Wire and BOM (Automotive)
		PCN25_0043_Form Material_Report Delta Qualification Matrix Qualification Results Summary
LTC3859ALEFE#PBF	PRODUCTION
LTC3859ALEFE#TRPBF	PRODUCTION
LTC3859ALEUHF#PBF	PRODUCTION
LTC3859ALEUHF#TRPBF	PRODUCTION
LTC3859ALHFE#PBF	PRODUCTION
LTC3859ALHFE#TRPBF	PRODUCTION
LTC3859ALHUHF#PBF	PRODUCTION
LTC3859ALHUHF#TRPBF	PRODUCTION
LTC3859ALHUHF#WPBF	PRODUCTION
LTC3859ALHUHF#WTRPBF	PRODUCTION
LTC3859ALIFE#PBF	PRODUCTION
LTC3859ALIFE#TRPBF	PRODUCTION
LTC3859ALIUHF#PBF	PRODUCTION
LTC3859ALIUHF#TRPBF	PRODUCTION
LTC3859ALIUHF#WPBF	PRODUCTION
LTC3859ALIUHF#WTRPBF	PRODUCTION
Apr 6, 2022 - 22_0068 Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL
		PCN22_0068_Form Material_Report Delta Qualification Matrix
LTC3859ALEFE#PBF	PRODUCTION
LTC3859ALEFE#TRPBF	PRODUCTION
LTC3859ALHFE#PBF	PRODUCTION
LTC3859ALHFE#TRPBF	PRODUCTION
LTC3859ALIFE#PBF	PRODUCTION
LTC3859ALIFE#TRPBF	PRODUCTION
LTC3859ALMPFE#PBF	PRODUCTION
LTC3859ALMPFE#TRPBF	PRODUCTION
Jul 31, 2020 - 20_0245 Notification of Wafer Fab Location Change for 0.6µm BICMOS Process Devices from ADI Milpitas (Hillview) to Vanguard Int. (Taiwan)
		PCN20_0245_Form Material_Report Delta Qualification Matrix Other Qualification Results Summary
LTC3859ALEFE#PBF	PRODUCTION
LTC3859ALEFE#TRPBF	PRODUCTION
LTC3859ALEUHF#PBF	PRODUCTION
LTC3859ALEUHF#TRPBF	PRODUCTION
LTC3859ALHFE#PBF	PRODUCTION
LTC3859ALHFE#TRPBF	PRODUCTION
LTC3859ALHUHF#PBF	PRODUCTION
LTC3859ALHUHF#TRPBF	PRODUCTION
LTC3859ALIFE#PBF	PRODUCTION
LTC3859ALIFE#TRPBF	PRODUCTION
LTC3859ALIUHF#PBF	PRODUCTION
LTC3859ALIUHF#TRPBF	PRODUCTION
LTC3859ALMPFE#PBF	PRODUCTION
LTC3859ALMPFE#TRPBF	PRODUCTION
LTC3859ALMPUHF#PBF	PRODUCTION
LTC3859ALMPUHF#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Circuit Monitors 1
LTC2960	RECOMMENDED FOR NEW DESIGNS	36V Nano-Current Two-Input Voltage Monitor
Protection Switches & Controllers 2
LTC4380	RECOMMENDED FOR NEW DESIGNS	Low Quiescent Current Surge Stopper
LTC4359	RECOMMENDED FOR NEW DESIGNS	Ideal Diode Controller with Reverse Input Protection
Switching Regulators & Controllers 1
LTC3899	RECOMMENDED FOR NEW DESIGNS	60V Low I_Q, Triple Output, Buck/Buck/Boost Synchronous Controller with PassThru

Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

LTC3859
LTC3859AL

LTpowerCAD 2

Design tools for the following parts are available in LTpowerCAD:

LTC3859AL(BOOST)
LTC3859AL(BUCK)

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

LTpowerCAD^® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

Evaluation Kits

LTC3859ALEUHF Demo Board | 4.5V ≤ VIN ≤ 36V; VOUT1: 5V @ 5A, VOUT2: 8.5V @ 3A, VOUT3: 10V @ 7A

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Product Details

Demonstration circuit 2122A is a triple output synchronous step-up/dual step-down supply featuring the LTC3859AL. This demonstration circuit is designed for two buck 5V/5A, 8.5V/3A outputs supplied by a boosted 10V/7A output. Benefiting from this feature, the buck outputs are able to maintain regulation over a wide input voltage range of 4.5V to 36V which is suitable for automotive or other battery fed applications. Also, the demonstration circuit uses a drop-in layout that the main buck circuit components fit in an area of ¾" by 1½", while the main boost circuit area is ¾" by 1¾". The package style for the LTC3859AL is a 38-pin exposed pad QFN package.

Resources

DC2122A - Design Files
3/7/2014

DC2122A - Schematic
3/7/2014

DC2122A - Demo Manual
3/7/2014

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