LTC3448 - 1.5MHz/2.25MHz, 600mA Synchronous Step-Down Regulator with LDO Mode


  • High Efficiency: Up to 96%
  • Very Low Quiescent Supply Current: 32µA During Linear Regulator Operation
  • 600mA Output Current (Buck Converter)
  • Optionally Operates as Linear Regulator Below 3mA-External or Automatic ON/OFF
  • 2.5V to 5.5V Input Voltage Range
  • 1.5MHz or 2.25MHz Constant Frequency Operation or External Synchronization
  • No Schottky Diode Required
  • Low Dropout Operation: 100% Duty Cycle
  • 0.6V Reference Allows Low Output Voltages
  • Shutdown Mode Draws < 1µA Supply Current
  • Current Mode Operation for Excellent Line and Load Transient Response
  • Overtemperature Protected
  • Low Profile (3mm × 3mm) 8-Lead DFN and 8-Lead MSOP Packages

Typical Application

LTC3448 Typical Application
LTC3448 Typical Application


The LTC3448 is a high efficiency, monolithic, synchronous buck regulator using a constant frequency, current mode architecture. Supply current during operation is only 32µA (linear regulator mode) and drops to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3448 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. At moderate output load levels, PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications.

The LTC3448 automatically switches into linear regulator operation at very low load currents to maintain <5mVP-P output voltage ripple. Supply current in this mode is typically 32µA. The switch to linear regulator mode occurs at a threshold of 3mA. Linear regulator operation can be set to on, off or automatic turn on/off.

Switching frequency is selectable at either 1.5MHz or 2.25MHz, allowing the use of small surface mount inductors and capacitors.

The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. The LTC3448 is available in a low profile 3mm × 3mm DFN package or thermally enhanced 8-lead MSOP.

Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131. Others pending.


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
LTC3448EDD#PBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3448EDD#TRPBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3448EMS8E#PBF MS-8E MS8E E 05-08-1662 Yes
LTC3448EMS8E#TRPBF MS-8E MS8E E 05-08-1662 Yes

LTC3448 Package Drawing
LTC3448 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
LTC3448EDD#PBF 3x3 DFN-8 E $2.93 $2.05 Yes
LTC3448EDD#TRPBF 3x3 DFN-8 E $2.15 Yes
LTC3448EMS8E#PBF MS-8E E $2.93 $2.05 Yes
LTC3448EMS8E#TRPBF MS-8E E $2.11 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
DC840A LTC3448EDD Demo Board | Vin=2.5V-5.5V, Vout= 1.2V/1.5V/1.8V @600mA Max Contact Factory
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Click here to view our complete list of demo boards


  • Cellular Telephones
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  • Wireless and DSL Modems
  • Digital Still Cameras
  • MP3 Players
  • Portable Instruments

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Design Tools


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