Features and Benefits
- 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.
- Palmtop Computers
- Handheld Instruments
- MP3 Players
- Digital Cameras
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (2)
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.
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.
Documentation & Resources
R415 Reliability Data3/23/2018
Efficient Buck-Boost Converter Ideal for Power Saving Modes and Wide Input Voltage Ranges6/1/2006 LT Journal
Taking Full Advantage of Very Low Dropout Linear Regulators12/1/2005 LT Journal
Versatile Buck-Boost Converter Offers High Efficiency in a Wide Variety of Applications5/1/2005 LT Journal
It Just Got Easier to Convert Lithium-Ion Battery Voltage to 3.3V with this Efficient Single Inductor Synchronous Buck-Boost Regulator3/1/2002 LT Journal
Tools & Simulations
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.