Overview
Features and Benefits
- 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
Product Details
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 efficiency 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.
| Options | Vout Switcher (V) | Vout VLDO | Auto 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 |
Applications
- PDAs/Palmtop PCs
- Digital Cameras
- Cellular Phones
- PC Cards
- Wireless and DSL Modems
- Other Portable Power Systems
Product Lifecycle
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)
Documentation
Reliability Data (1)
Evaluation Kit Manuals (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.
Models for the following parts are available in LTspice:
Reference Materials
Press Releases (1)
Design Resources
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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.
