LTC3541-3 - High Efficiency Buck + VLDO Regulator
Features
- High Efficiency 500mA Buck Plus 300mA VLDO Regulator
- Auto Start-Up Powers VLDO/Linear Regulator Output Prior to Buck Output
- Independent 500mA High Efficiency Buck (VIN: 2.7V to 5.5V)
- 300mA VLDO Regulator with 30mA Standalone Mode
- No External Schottky Diodes Required
- Fixed Buck Output Voltage: 1.8V
- VLDO Input Voltage Range (LVIN: 1.675V to 5.5V)
- Fixed VLDO Output Voltage: 1.575V
- Selectable Fixed Frequency, Pulse-Skip Operation or Burst Mode Operation
- Short-Circuit Protected
- Current Mode Operation for Excellent Line and Load Transient Response
- Shutdown Current: <3μA
- Constant Frequency Operation: 2.25MHz
- Low Dropout Buck Operation: 100% Duty Cycle
- Small, Thermally Enhanced, 10-Lead (3mm × 3mm) DFN Package
Typical Application
Description
The LTC3541-3 combines a synchronous buck DC/ DC converter with a very low dropout linear regulator (VLDOTM regulator) and internal feedback resistor networks to provide two output voltages from a single input voltage with minimum external components. When configured for dual output operation, the LTC3541-3’s auto start-up feature will bring the 1.575V VLDO/linear regulator output into regulation in a controlled manner prior to enabling the 1.8V buck output without the need for external pin control. The 300mA VLDO/linear regulator output will source only 30mA until the buck output achieves regulation. The input voltage range is ideally suited for applications powered from a Li-Ion battery and 5V or 3.3V rails.
The synchronous buck converter provides a high efficiency output, typically 90%. It can provide up to 500mA of 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 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 |
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-3#PBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LTC3541EDD-3#TRPBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
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-3#PBF | 3x3 DFN-10 | E | $2.70 | $1.89 | Yes | |
| LTC3541EDD-3#TRPBF | 3x3 DFN-10 | E | $1.95 | Yes | ||
| Buy Now • Request Samples | ||||||
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.Click here to view our complete list of demo boards
Applications
- Digital Cameras
- Cellular Phones
- PC Cards
- Wireless and DSL Modems
- Other Portable Power Systems
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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
Models for the following parts are available in LTspice:
LTC3541
LTC3541-1
LTC3541-2
LTC3541-3
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
