LTC3444 - Micropower Synchronous Buck-Boost DC/DC Converter for WCDMA Applications


  • Optimized Features for WCDMA Handsets
  • Regulated Output with Input Voltages Above, Below, or Equal to the Output
  • 0.5V to 5V Output Range
  • Up to 400mA Continuous Output Current From a Single Lithium-Ion Cell
  • Minimal External Components
  • 1.5MHz Fixed Frequency Operation
  • Internal Loop Compensation for Fast Response <25μs Full Scale Output Slewing; COUT 4.7μF
  • Output Disconnect in Shutdown
  • 2.75V to 5.5V Input
  • <1μA Shutdown Current
  • Internal Soft-Start
  • Output Overvoltage Protection
  • Single Inductor, No Schottky Diodes Required
  • Small, Thermally Enhanced 8-Lead (3mm × 3mm) DFN Package

Typical Application

LTC3444 Typical Application
LTC3444 Typical Application


The LTC3444 is a highly efficient, fixed frequency, buck-boost DC/DC converter, which operates from input voltages above, below, and 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 a single Lithium-Ion or multi-cell applications where the output voltage can vary over a wide range.

The LTC3444 has been optimized for use in 3G WCDMA applications. A unique design yields high efficiency at very low output voltages while also eliminating external components. The high speed error amplifier provides the fast transient response required to slew the RF power amplifier from standby to transmit and transmit to stand by power levels. Output overvoltage protection protects the RF power amplifier.

Operating frequency is internally set to 1.5MHz to minimize external component size while maximizing efficiency. Other features include <1μA shutdown current, internal soft-start, peak current limit and thermal shutdown.

The LTC3444 is available in a small, thermally enhanced 8-lead (3mm × 3mm) DFN package.


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
LTC3444EDD#PBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3444EDD#TRPBF 3x3 DFN-8 DD E 05-08-1698 Yes

LTC3444 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
LTC3444EDD#PBF 3x3 DFN-8 E $3.43 $2.40 Yes
LTC3444EDD#TRPBF 3x3 DFN-8 E $2.46 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
DC901A LTC3444EDD Demo Board | Synchronous Buck-Boost, for CDMA & HSDPA, 3.1V ≤VIN ≤ 5V, Vout = 0.8V to 4.2V @ 400mA $100.00
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Click here to view our complete list of demo boards


  • WCDMA Applications–3G Handsets with High Speed Data Rate Capability
  • MP3 Players
  • Digital Cameras

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Design Tools


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