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
AEC-Q100 data available for specific packages
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.
| LT8705 | |
| LT8705A | Improved, pin-to-pin compatible version of LT8705. Recommended for all new designs |
Packaging
CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.
For complete and up to date package information and drawings, please refer to our packaging page
| Part Number | Package | Code | Temp | Package Drawing |
RoHS |
|---|---|---|---|---|---|
| LT8705EFE#PBF | TSSOP-38 | FE | E | 05-08-1865 | Yes |
| LT8705EFE#TRPBF | TSSOP-38 | FE | E | 05-08-1865 | Yes |
| LT8705EUHF#PBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LT8705EUHF#TRPBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LT8705HFE#PBF | TSSOP-38 | FE | H | 05-08-1865 | Yes |
| LT8705HFE#TRPBF | TSSOP-38 | FE | H | 05-08-1865 | Yes |
| LT8705IFE#PBF | TSSOP-38 | FE | I | 05-08-1865 | Yes |
| LT8705IFE#TRPBF | TSSOP-38 | FE | I | 05-08-1865 | Yes |
| LT8705IUHF#PBF | 5x7 QFN-38 | UHF | I | 05-08-1701 | Yes |
| LT8705IUHF#TRPBF | 5x7 QFN-38 | UHF | I | 05-08-1701 | Yes |
| LT8705MPFE#PBF | TSSOP-38 | FE | MP | 05-08-1865 | Yes |
| LT8705MPFE#TRPBF | TSSOP-38 | FE | MP | 05-08-1865 | Yes |
Order Info
- Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LT8705EFE#PBF | TSSOP-38 | E | $8.50 | $5.95 | Yes | |
| LT8705EFE#TRPBF | TSSOP-38 | E | $6.01 | Yes | ||
| LT8705EUHF#PBF | 5x7 QFN-38 | E | $8.50 | $5.95 | Yes | |
| LT8705EUHF#TRPBF | 5x7 QFN-38 | E | $6.01 | Yes | ||
| LT8705HFE#PBF | TSSOP-38 | H | $9.76 | $6.83 | Yes | |
| LT8705HFE#TRPBF | TSSOP-38 | H | $6.89 | Yes | ||
| LT8705IFE#PBF | TSSOP-38 | I | $9.40 | $6.58 | Yes | |
| LT8705IFE#TRPBF | TSSOP-38 | I | $6.64 | Yes | ||
| LT8705IUHF#PBF | 5x7 QFN-38 | I | $9.40 | $6.58 | Yes | |
| LT8705IUHF#TRPBF | 5x7 QFN-38 | I | $6.64 | Yes | ||
| LT8705MPFE#PBF | TSSOP-38 | MP | $25.37 | $17.76 | Yes | |
| LT8705MPFE#TRPBF | TSSOP-38 | MP | $17.82 | Yes | ||
| Buy Now • Request Samples | ||||||
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 | |
| Buy Now | |||
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LT8705IUHF#PBF | 5x7 QFN-38 | I | $9.40 | $6.58 | Yes | |
| LT8705IUHF#TRPBF | 5x7 QFN-38 | I | $6.64 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- High Voltage Buck-Boost Converters
- Input or Output Current Limited Converters
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Design Tools
LTspice
LTspice® software 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
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
- Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
- Step 3: If LTspice 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:
LT8705
LT8705A
LTpowerCAD
The LTpowerCAD 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
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
