LTC3785 - 10V, High Efficiency, Synchronous, No RSENSE Buck-Boost Controller

Features

  • Single Inductor Architecture Allows VIN Above, Below or Equal to VOUT
  • 2.7V to 10V Input and Output Range
  • Up to 96% Efficiency
  • Up to 10A of Output Current
  • All N-channel MOSFETs, No RSENSE
  • True Output Disconnect During Shutdown
  • Programmable Current Limit and Soft-Start
  • Optional Short-Circuit Shutdown Timer
  • Output Overvoltage and Undervoltage Protection
  • Programmable Frequency: 100kHz to 1MHz
  • Selectable Burst Mode® Operation
  • Available in 24-Lead (4mm × 4mm) Exposed Pad QFN Package

Typical Application

LTC3785 Typical Application
LTC3785 Typical Application

Description

The LTC3785 is a high power synchronous buck-boost controller that drives all N-channel power MOSFETs from input voltages above, below and equal to the output voltage. With an input range of 2.7V to 10V, the LTC3785 is well suited for a wide variety of single or dual cell Li-Ion or multicell alkaline/NiMH applications.

The operating frequency can be programmed from 100kHz to 1MHz. The soft-start time and current limit are also programmable. The soft-start capacitor doubles as the fault timer which can program the IC to latch off or recycle after a determined off time. Burst Mode operation is user controlled and can be enabled by driving the MODE pin high.

Protection features include foldback current limit, shortcircuit and overvoltage protection.

  Power Good
LTC3785 No
LTC3785-1 Yes

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
LTC3785EUF#PBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC3785EUF#TRPBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC3785IUF#PBF 4x4 QFN-24 UF I 05-08-1697 Yes
LTC3785IUF#TRPBF 4x4 QFN-24 UF I 05-08-1697 Yes


LTC3785 Package Drawing

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
LTC3785EUF#PBF 4x4 QFN-24 E $5.09 $3.56 Yes
LTC3785EUF#TRPBF 4x4 QFN-24 E $3.62 Yes
LTC3785IUF#PBF 4x4 QFN-24 I $5.54 $3.88 Yes
LTC3785IUF#TRPBF 4x4 QFN-24 I $3.94 Yes
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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
DC957A LTC3785EUF Demo Board | No Rsense, 2.7V ≤ VIN ≤ 10V, Vout = 3.3V @ 3A $150.00
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Click here to view our complete list of demo boards

Applications

  • Palmtop Computers
  • Handheld Instruments
  • Wireless Modems
  • Cellular Telephones

Product Notifications

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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:
LTC3785
LTC3785-1

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:
LTC3785

Technical Support