LTC3440

PRODUCTION

Micropower Synchronous Buck-Boost DC/DC Converter

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Overview

  • 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

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 0.19Ω N-channel MOSFET switches and two 0.22Ω 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.

Applications

  • Palmtop Computers
  • Handheld Instruments
  • MP3 Players
  • Digital Cameras
LTC3440
Micropower Synchronous Buck-Boost DC/DC Converter
Li-Ion to 3.3V at 600mA Buck-Boost Converter Efficiency vs VIN Product Package 1 Product Package 2
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 2

Design Note 2

Technical Articles 4

Data Sheet

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

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Software Resources

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Tools & Simulations

LTspice 1

Models for the following parts are available in LTspice:

  • LTC3440
LTspice

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.

Evaluation Kits

DC425B

LTC3440EMS Demo Board (MSOP)| 1MHz, Synchronous Buck-Boost, VIN = 2.5V to 5.5V, VOUT = 3.3V @ 0.6A

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Product Details

Demonstration Circuit 425B is a constant-frequency synchronous Buck-Boost converter using the LTC3440. The input range is from 2.5V to 5.5V, making it ideal for single-cell lithium-ion or three-cell NiCd/NiMH battery applications. For 2.7V minimum input voltage, this converter can provide up to 600mA load current. The output voltage is set at 3.3V. A different output voltage in the range of 2.5V to 5.5V can be obtained by changing one of the feedback resistors.


eval board
schematic 1
DC797A

LTC3440EDD Demo Board (DFN) | 1MHz, Synchronous Buck-Boost, VIN = 2.5V to 5.5V, VOUT = 3.3V @ 0.6A

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Product Details

Demonstration Circuit 797 is a constant-frequency synchronous Buck-Boost converter using the LTC3440EDD in the 3mm × 3mm DFN-10 package. The input range is from 2.5V to 5.5V, making it ideal for single-cell Lithium-Ion or three-cell NiCd/NiMH battery applications. For 2.7V minimum input voltage, this converter can provide up to 600mA load current. The output voltage is set at 3.3V. A different output voltage in the range of 2.5V to 5.25V can be obtained by changing one of the feedback resistors.
DC425B
LTC3440EMS Demo Board (MSOP)| 1MHz, Synchronous Buck-Boost, VIN = 2.5V to 5.5V, VOUT = 3.3V @ 0.6A
DC797A
LTC3440EDD Demo Board (DFN) | 1MHz, Synchronous Buck-Boost, VIN = 2.5V to 5.5V, VOUT = 3.3V @ 0.6A
DC797A - Schematic

Latest Discussions

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LTC 3440 LTspice Simulation (using macromodel's test fixture) works w/ 100 ohm load resistor (0.033A) but not 13.2 Ohms (.25A)
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