LTC3859

RECOMMENDED FOR NEW DESIGNS

Low I_Q, Triple Output, Buck/Buck/Boost Synchronous Controller

Data Sheet (Rev. C) Product Selection Table

Part Models: 8
1ku List Price: Starting From $5.19

Viewing:

Overview

Dual Buck Plus Single Boost Synchronous Controllers
Outputs Remain in Regulation Through Cold Crank Down to 2.5V
Low Operating I_Q: 55μA (One Channel On)
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

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: 14μA
Small 38-Pin 5mm × 7mm QFN and TSSOP Packages

The LTC3859 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 LTC3859 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 LTC3859 can operate from an input supply as low as 2.5V after start-up.

The 55μA 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 LTC3859 features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator.

Independent TRACK/SS pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/ MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.


	Quiescent Current (Burst Mode)	Notes
LTC3859AL	28μA-One channel on, Buck 38μA-All three channels on	Internal clamp on the INTV_CC pin
LTC3859A	55μA-One channel on, Buck 80μA-All three channels on	Internal clamp on the INTV_CC 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

Part Models: 8
1ku List Price: Starting From $5.19

Documentation

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
LTC3859EFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859EFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859EUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859EUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859IFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859IFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859IUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3859IUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

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
LTC3859EFE#PBF	PRODUCTION
LTC3859EFE#TRPBF	PRODUCTION
LTC3859EUHF#PBF	PRODUCTION
LTC3859EUHF#TRPBF	PRODUCTION
LTC3859IFE#PBF	PRODUCTION
LTC3859IFE#TRPBF	PRODUCTION
LTC3859IUHF#PBF	PRODUCTION
LTC3859IUHF#TRPBF	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
LTC3859EFE#PBF	PRODUCTION
LTC3859EFE#TRPBF	PRODUCTION
LTC3859IFE#PBF	PRODUCTION
LTC3859IFE#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
LTC3859EFE#PBF	PRODUCTION
LTC3859EFE#TRPBF	PRODUCTION
LTC3859EUHF#PBF	PRODUCTION
LTC3859EUHF#TRPBF	PRODUCTION
LTC3859IFE#PBF	PRODUCTION
LTC3859IFE#TRPBF	PRODUCTION
LTC3859IUHF#PBF	PRODUCTION
LTC3859IUHF#TRPBF	PRODUCTION

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

Software Resources

Can't find the software or driver you need?

Request a Driver/Software

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
LTC4359	RECOMMENDED FOR NEW DESIGNS	Ideal Diode Controller with Reverse Input Protection
LTC2955	RECOMMENDED FOR NEW DESIGNS	Pushbutton On/Off Controller with Automatic Turn-On
Switching Regulators & Controllers 1
LTC3899	RECOMMENDED FOR NEW DESIGNS	60V Low I_Q, Triple Output, Buck/Buck/Boost Synchronous Controller with PassThru

Parts	Product Life Cycle	Description
LTC3859AL	PRODUCTION	Triple Output, Buck/Buck/Boost Synchronous Controller with 28μA Burst Mode I_Q

Tools & Simulations

LTspice 1

LTC3859 Demo Circuit - High Efficiency Boost / Dual Buck Supply

Models for the following parts are available in LTspice:

LTC3859
LTC3859AL

LTpowerCAD

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.

Latest Discussions

2 Years Ago