LTC3541 - High Efficiency Buck + VLDO Regulator

Features

  • High Efficiency, 500mA Buck Plus 300mA VLDO Regulator
  • Auto Start-Up Powers Buck Output Prior to VLDO/Linear Regulator Output
  • Independent High Efficiency, 500mA Buck (VIN: 2.7V to 5.5V)
  • 300mA VLDO Regulator with 30mA Standalone Mode
  • No External Schottky Diodes Required
  • Buck Output Voltage Range: 0.8V to 5V
  • VLDO Input Voltage Range (LVIN): 0.9V to 5.5V
  • VLDO Output Voltage Range VLDO: 0.4V to 4.1V
  • Selectable Fixed Frequency, Pulse-Skip Operation or Burst Mode® Operation
  • Short-Circuit Protected
  • Current Mode Operation for Excellent Line and Load
  • Transient Response
  • Constant Frequency Operation: 2.25MHz
  • Low Dropout Buck Operation: 100% Duty Cycle
  • Small, Thermally Enhanced, 10-Lead (3mm × 3mm) DFN Package

Typical Application

LTC3541 Typical Application
LTC3541 Typical Application

Description

The LTC3541 combines a synchronous buck DC/DC converter with a very low dropout linear regulator (VLDO) to provide up to two output voltages from a single input voltage with minimal external components. When configured for dual output operation, the LTC3541’s auto start-up feature will bring the Buck output into regulation in a controlled manner prior to enabling the VLDO regulator output without the need for external pin control. VLDO/ linear regulator output prior to Buck output sequencing may also be obtained via external pin control. The input voltage range is ideally suited for Li-Ion battery-powered applications, as well as powering sub-3.3V logic from 5V or 3.3V rails.

The synchronous buck converter provides a high efficiency output, typically 90%, capable of providing up to 500mA of continuous output current while switching at 2.25MHz, allowing the use of small surface mount inductors and capacitors. A mode-select pin allows Burst Mode operation to be enabled for higher effi ciency at light load currents, or disabled for lower noise, constant frequency operation.

The VLDO regulator provides a low noise, low voltage output capable of providing up to 300mA of continuous output current using only a 2.2μF ceramic capacitor. The input supply voltage of the VLDO regulator (LVIN) may come from the buck regulator or a separate supply.

OptionsVout Switcher (V)Vout VLDOAuto Start Up Sequencing
LTC3541 Adj down to 0.8V Adj down to 0.4V Switcher, then VLDO
LTC3541-1 Adj down to 0.8V Adj down to 0.4V VLDO, then switcher
LTC3541-2 1.875V fixed 1.5V fixed Switcher, then VLDO
LTC3541-3 1.8V fixed 1.575 fixed VLDO, then switcher

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
LTC3541EDD#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3541EDD#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes


LTC3541 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
LTC3541EDD#PBF 3x3 DFN-10 E $2.70 $1.89 Yes
LTC3541EDD#TRPBF 3x3 DFN-10 E $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
DC970A-A LTC3541 Demo Board | 3V ≤ VIN ≤ 5.5V, Vout1 (Buck) = 1.8V or 2.5V @ 500mA, Vout2 (VLDO) = 0.8V/1.2V/1.5V/1.8V @ 300mA $100.00
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Click here to view our complete list of demo boards

Applications

  • PDAs/Palmtop PCs
  • Digital Cameras
  • Cellular Phones
  • PC Cards
  • Wireless and DSL Modems
  • Other Portable Power Systems

Product Notifications

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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:
LTC3541
LTC3541-1
LTC3541-2
LTC3541-3

Technical Support