LTC3547 - Dual Monolithic 300mA Synchronous Step-Down Regulator


  • High Efficiency Dual Step-Down Outputs: Up to 96%
  • 300mA Output Current per Channel at VIN = 3V
  • Automatic Low Ripple Burst Mode Operation (20mVP-P).
  • Only 40µA Quiescent Current During Operation (Both Channels)
  • 2.25MHz Constant-Frequency Operation
  • 2.5V to 5.5V Input Voltage Range
  • Low Dropout Operation: 100% Duty Cycle
  • Internally Compensated for All Ceramic Capacitors
  • Independent Internal Soft-Start for Each Channel
  • Current Mode Operation for Excellent Line and Load Transient Response
  • 0.6V Reference Allows Low Output Voltages
  • Short-Circuit Protected
  • Ultralow Shutdown Current: IQ < 1µA
  • Low Profi le (0.75mm) 8-Lead 3mm × 2mm DFN Package

Typical Application

LTC3547 Typical Application
LTC3547 Typical Application


The LTC3547 is a dual, 2.25MHz, constant-frequency, synchronous step-down DC/DC converter in a tiny 3mm × 2mm DFN package. 100% duty cycle provides low dropout operation, extending battery life in portable systems. Low output voltages are supported with the 0.6V feedback reference voltage. Each regulator can supply 300mA continuous output current.

The input voltage range is 2.5V to 5.5V, making it ideal for Li-Ion and USB powered applications. Supply current during operation is only 40µA and drops to < 1µA in shutdown. Automatic Burst Mode® operation increases efficiency at light loads, further extending battery life.

An internally set 2.25MHz switching frequency allows the use of tiny surface mount inductors and capacitors. Internal soft-start reduces inrush current during startup. All outputs are internally compensated to work with ceramic capacitors. The LTC3547 is available in a low profile (0.75mm) 3mm × 2mm DFN package.The LTC3547is also available in a fixed output voltage configuration,eliminating the need for the external feedback networks


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
LTC3547EDDB-1#PBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3547EDDB-1#TRMPBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3547EDDB-1#TRPBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3547EDDB#PBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3547EDDB#TRMPBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3547EDDB#TRPBF 3x2 DFN-8 DDB E 05-08-1702 Yes

LTC3547 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
LTC3547EDDB-1#PBF 3x2 DFN-8 E $2.79 Yes
LTC3547EDDB-1#TRMPBF 3x2 DFN-8 E $2.79 $2.00 Yes
LTC3547EDDB-1#TRPBF 3x2 DFN-8 E $2.79 $1.95 Yes
LTC3547EDDB#PBF 3x2 DFN-8 E $2.79 Yes
LTC3547EDDB#TRMPBF 3x2 DFN-8 E $2.79 $2.00 Yes
LTC3547EDDB#TRPBF 3x2 DFN-8 E $2.79 $1.95 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
DC1013A LTC3547EDDB | Dual Monolithic Sync. Buck Converter $100.00
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Click here to view our complete list of demo boards


  • Cellular Telephones
  • Digital Still Cameras
  • Wireless and DSL Modems
  • PDAs/Palmtop PCs
  • Portable Media Players

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Design Tools


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:

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  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
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