LTC3547 - Dual Monolithic 300mA Synchronous Step-Down Regulator

Features

  • 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

Description

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

Packaging

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
Drawing
RoHS
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
(1-99)
Price
(1k)*
RoHS
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
Buy NowRequest Samples
* 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
Buy Now
Click here to view our complete list of demo boards

Applications

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

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.

Design Tools

LTspice

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:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LTC3547
LTC3547-1
LTC3547B
LTC3547B-1

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

To open the project file for this circuit:

Design tools for the following parts are available in LTpowerCAD:
LTC3547

Technical Support