LT8705 - 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller

Features

  • Single Inductor Allows VIN Above, Below, or Equal to Regulated VOUT
  • VIN Range 2.8V (Need EXTVCC > 6.4V) to 80V
  • VOUT 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

Typical Application

LT8705 Typical Application
LT8705 Typical Application

Description

The LT®8705 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.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

QFN-38, TSSOP-38

LT8705 Package Drawing
LT8705 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LT8705EFE#PBF TSSOP 38 E $8.50 $5.95 View
LT8705EFE#TRPBF TSSOP 38 E $6.01 View
LT8705EUHF#PBF QFN 38 E $8.50 $5.95 View
LT8705EUHF#TRPBF QFN 38 E $6.01 View
LT8705HFE#PBF TSSOP 38 H $9.76 $6.83 View
LT8705HFE#TRPBF TSSOP 38 H $6.89 View
LT8705IFE#PBF TSSOP 38 I $9.40 $6.58 View
LT8705IFE#TRPBF TSSOP 38 I $6.64 View
LT8705IUHF#PBF QFN 38 I $9.40 $6.58 View
LT8705IUHF#TRPBF QFN 38 I $6.64 View
LT8705MPFE#PBF TSSOP 38 MP $25.37 $17.76 View
LT8705MPFE#TRPBF TSSOP 38 MP $17.82 View
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1924A LT8705EUHF Demo Board | 36V ≤ VIN ≤ 80V; Vout = 48V @ 5A . $250.00
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Click here to view our complete list of demo boards

Applications

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

Product Notifications

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Design Tools

LTpowerCAD

The LTpowerCAD II design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:
LT8705

LTspiceIV

LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice IV

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice IV
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice IV does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As". After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice IV:
LT8705

Technical Support