Features and Benefits
- High Efficiency, 500mA Buck Plus 300mA VLDO Regulator
- Auto Start-Up Powers Buck Output Prior to VLDO/Linear Regulator 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: 1.875V
- VLDO Input Voltage Range (LVIN: 1.6V to 5.5V)
- Fixed VLDO Output Voltage: 1.5V
- 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
The LTC3541-2 combines a synchronous buck DC/DC converter with a very low dropout linear regulator (VLDO™regulator) and internal feedback resistor networks to provide two output voltages from a single input voltage with minimal external components. When configured for dual output operation, the LTC3541-2’s auto start-up feature will bring the 1.875V buck output into regulation in a controlled manner, prior to enabling the 1.5V VLDO output without the need for external pin control. The 1.5V VLDO/linear regulator output prior to 1.875V buck output sequencing may also be obtained via external pin control. The input voltage range is ideally suited for Li-Ion battery applications powering sub-3.3V logic from 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 output 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|
- 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.
Tools & Simulations
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.
Models for the following parts are available in LTspice:
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