Overview

Features and Benefits

  • 1.6V to 5.5V Input Voltage Range
  • Internal Soft-Start
  • Low Ripple Burst Mode® Operation
    • Output Ripple: <20mVP-P
    • IQ: 50µA
  • 2.25MHz Constant-Frequency Operation
  • High Effi ciency: Up to 93%
  • 250mA Output Current (VIN = 1.8V, VOUT = 1.2V)
  • 450mA Peak Inductor Current
  • No Schottky Diode Required
  • Low Dropout Operation: 100% Duty Cycle
  • 0.611V Reference Voltage
  • Stable with Ceramic Capacitors
  • Shutdown Mode Draws <1µA Supply Current
  • Current Mode Operation for Excellent Line and Load Transient Response
  • Overtemperature Protection
  • Available in a Low Profi le (0.75mm) 6-Lead (2mm × 3mm) DFN Package

Product Details

The LTC3549 is a high efficiency, monolithic synchronous buck regulator using a constant-frequency, current mode architecture. The output voltage is adjusted via an external resistor divider.

A fixed switching frequency of 2.25MHz is supported. This switching frequency allows the use of small surface mount inductors and capacitors, including ceramics.

Supply current during Burst Mode operation is only 50µA dropping to < 1µA in shutdown. The 1.6V to 5.5V input voltage range makes the LTC3549 ideally suited for single cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd or NiMH battery-powered applications. 100% duty cycle capability provides low dropout operation, extending battery life in portable systems. Burst Mode operation can be user-enabled, increasing efficiency at light loads, further extending battery life.

The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Internal soft-start offers controlled output voltage rise time at startup without the need for external components.

Applications

  • 2 AA-Cell Applications
  • Cellular Phones
  • Digital Cameras
  • MP3 Players

Product Lifecycle icon-recommended 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 (1)

Tools & Simulations

LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, 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.

LTspice

Models for the following parts are available in LTspice:

LTC3549

LTpowerCAD

LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

To open the project file for this circuit:

Step 1: Download and install LTpowerCAD on your computer.

Step 2: Click on the link(s) in the section below to download part-specific project files.

Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.

LTPowerCAD

Design tools for the following parts are available in LTpowerCAD:

LTC3549

Product Recommendations

LTC3549 Companion Parts

Recommended Related Parts

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

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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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


Price Table Help

 

Evaluation Boards Pricing displayed is based on 1-piece.
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.