LT8705

PRODUCTION

80V V_IN and V_OUT Synchronous 4-Switch Buck-Boost DC/DC Controller

Part Models: 12
1ku List Price: Starting From $7.07

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Part Details

Single Inductor Allows V_IN Above, Below, or Equal to Regulated V_OUT
V_IN Range 2.8V (Need EXTV_CC > 6.4V) to 80V
V_OUT Range: 1.3V to 80V
Quad N-Channel MOSFET Gate Drivers
Synchronous Rectification: Up to 98% Efficiency
Input and Output Current Monitor Pins
Synchronizable Fixed Frequency: 100kHz to 400kHz
Integrated Input Current, Input Voltage, Output and Output Voltage Feedback Loops
Clock Output Usable To Monitor Die Temperature
Available in 38-Lead (5mm × 7mm) QFN and TSSOP Packages with the TSSOP Modified for Improve Voltage Operation

The LT8705 is a high performance buck-boost switching regulator controller that operates from input voltages above, below or equal to the output voltage. The part has integrated input current, input voltage, output current and output voltage feedback loops. With a wide 2.8V to 80V input and 1.3V to 80V output range, the LT8705 is compatible with most solar, automotive, telecom and battery-powered systems.

The LT8705 includes servo pins to indicate which feedback loops are active. The MODE pin selects among Burst Mode^® operation, discontinuous or continuous conduction mode at light loads. Additional features include a 3.3V/12mA LDO, a synchronizable fixed operating frequency, onboard gate drivers, adjustable UVLO, along with input and output current monitoring with programmable maximum levels.


LT8705
LT8705A	Improved, pin-to-pin compatible version of LT8705. Recommended for all new designs

Applications

High Voltage Buck-Boost Converters
Input or Output Current Limited Converters

Part Models: 12
1ku List Price: Starting From $7.07

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
LT8705EFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705EFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705EUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705EUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705HFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705HFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705IFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705IFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705IUHF#PBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705IUHF#TRPBF	38-Lead QFN (5mm x 7mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705MPFE#PBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT8705MPFE#TRPBF	38-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Feb 14, 2025 - 25_0017 Bond Wire Change from Gold to Copper
		PCN25_0017_Form Material_Report Qualification Results Summary
LT8705EFE#PBF	PRODUCTION
LT8705EFE#TRPBF	PRODUCTION
LT8705HFE#PBF	PRODUCTION
LT8705HFE#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
LT8705EFE#PBF	PRODUCTION
LT8705EFE#TRPBF	PRODUCTION
LT8705HFE#PBF	PRODUCTION
LT8705HFE#TRPBF	PRODUCTION
LT8705IFE#PBF	PRODUCTION
LT8705IFE#TRPBF	PRODUCTION
LT8705MPFE#PBF	PRODUCTION
LT8705MPFE#TRPBF	PRODUCTION

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

Hardware Ecosystem

Parts	Product Life Cycle	Description
External Power Switch Buck-Boost Controllers 1
LT8390	RECOMMENDED FOR NEW DESIGNS	60V Synchronous 4-Switch Buck-Boost Controller with Spread Spectrum
Surge Stopper, Overvoltage, and Overcurrent Protection 1
LTC4366	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper

Parts	Product Life Cycle	Description
LT8390A	RECOMMENDED FOR NEW DESIGNS	60V 2MHz Synchronous 4-Switch Buck-Boost Controller with Spread Spectrum
LT8390	RECOMMENDED FOR NEW DESIGNS	60V Synchronous 4-Switch Buck-Boost Controller with Spread Spectrum
LT8705A	RECOMMENDED FOR NEW DESIGNS	80V V_IN and V_OUT Synchronous 4-Switch Buck-Boost DC/DC Controller

Tools & Simulations

LTspice 3

Models for the following parts are available in LTspice:

LT8705
LT8705A

LTpowerCAD 1

LT8705 Project - Telecom Voltage Stabilizer (36-80V to 48V @ 5A)

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

LT8705EUHF Demo Board | 36V ≤ VIN ≤ 80V; VOUT = 48V @ 5A

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Product Details

Demonstration circuit 1924A is a high performance buckboost converter featuring the LT8705 that can operate from input voltages above, below or equal to the output voltage. The demo board input range is 36V to 80V. The output is optimized for 48V at 5A, with the output current limit set at 7A. (The circuit will operate with lower input voltage than 36V if load current is reduced).

Resources

DC1924A - Design Files
1.00M

DC1924A - Demo Manual
514.00K

DC1924A - Schematic
63.00K

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LT8705

Part Details

Documentation

Data Sheet 1

Reliability Data 1

User Guide 1

Application Note 1

Design Note 1

Technical Articles 1

Video 2

Solutions Bulletin & Brochure 1

Product Selector Card 1