LTC3440 - Micropower Synchronous Buck-Boost DC/DC Converter

Features

  • Single Inductor
  • Fixed Frequency Operation with Battery Voltages
  • Above, Below or Equal to the Output
  • Synchronous Rectification: Up to 96% Efficiency
  • 25µA Quiescent Current in Burst Mode® Operation
  • Up to 600mA Continuous Output Current
  • No Schottky Diodes Required (VOUT < 4.3V)
  • VOUT Disconnected from VIN During Shutdown
  • 2.5V to 5.5V Input and Output Range
  • Programmable Oscillator Frequency from 300kHz to 2MHz
  • Synchronizable Oscillator
  • Burst Mode Enable Control
  • <1µA Shutdown Current
  • Small Thermally Enhanced 10-Pin MSOP and (3mm × 3mm) DFN Packages

Typical Application

LTC3440 Typical Application
LTC3440 Typical Application

Description

The LTC3440 is a high efficiency, fixed frequency, Buck-Boost DC/DC converter that operates from input voltages above, below or equal to the output voltage. The topology incorporated in the IC provides a continuous transfer function through all operating modes, making the product ideal for single lithium-ion, multicell alkaline or NiMH applications where the output voltage is within the battery voltage range.

The device includes two 0.19Ohm N-channel MOSFET switches and two 0.22Ohm P-channel switches. Switching frequencies up to 2MHz are programmed with an external resistor and the oscillator can be synchronized to an external clock. Quiescent current is only 25µA in Burst Mode operation, maximizing battery life in portable applications. Burst Mode operation is user controlled and can be enabled by driving the MODE/SYNC pin high. If the MODE/SYNC pin has either a clock or is driven low, then fixed frequency switching is enabled.

Other features include a 1µA shutdown, soft-start control, thermal shutdown and current limit. The LTC3440 is available in the 10-pin thermally enhanced MSOP package.

Protected by U.S. Patents including 6404251, 6166527.

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
LTC3440EDD#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3440EDD#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3440EMS#PBF MS-10 MS E 05-08-1661 Yes
LTC3440EMS#TRPBF MS-10 MS E 05-08-1661 Yes


LTC3440 Package Drawing
LTC3440 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
LTC3440EDD#PBF 3x3 DFN-10 E $3.38 $2.84 Yes
LTC3440EDD#TRPBF 3x3 DFN-10 E $2.94 Yes
LTC3440EMS#PBF MS-10 E $3.24 $2.74 Yes
LTC3440EMS#TRPBF MS-10 E $2.80 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
DC425B LTC3440EMS Demo Board (MSOP)| 1MHz, Synchronous Buck-Boost, Vin = 2.5V to 5.5V, Vout = 3.3V @ 0.6A $75.00
DC797A LTC3440EDD Demo Board (DFN) | 1MHz, Synchronous Buck-Boost, Vin = 2.5V to 5.5V, Vout = 3.3V @ 0.6A $150.00
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Click here to view our complete list of demo boards

Applications

  • Palmtop Computers
  • Handheld Instruments
  • MP3 Players
  • Digital Cameras

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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:
LTC3440

Technical Support