LTC3541-2 Datasheet | Linear Technology

High Efficiency Buck + VLDO Regulator Features nn High Efficiency, 500m A Buck Plus 300m A VLDO Regulator nn Auto Start-Up Powers Buck Output Prior to VLDO/ Linear Regulator Output nn Independent 500m A High Efficiency Buck (VIN: 2.7V to 5.5V) nn 300m A VLDO Regulator with 30m A Standalone Mode nn No External Schottky Diodes Required nn Fixed Buck Output Voltage: 1.875V nn VLDO Input Voltage Range (LVIN: 1.6V to 5.5V) nn Fixed VLDO Output Voltage: 1.5V nn Selectable Fixed Frequency, Pulse-Skip Operation nn or Burst Mode® Operation nn Short-Circuit Protected nn Current Mode Operation for Excellent Line and Load Transient Response nn Shutdown Current: <3µA nn Constant Frequency Operation: 2.25MHz nn Low Dropout Buck Operation: 100% Duty Cycle nn Small, Thermally Enhanced, 10-Lead (3mm × 3mm) DFN Package APPLICATIONS nn Digital Cameras nn Cellular Phones nn PC Cards nn Wireless and DSL Modems nn Other Portable Power Systems DESCRIPTION The LTC®3541-2 bines a synchronous buck DC/ DC converter with a very low dropout linear regulator (VLDOTMregulator) and internal feedback resistor networks to provide two output voltages from a single input voltage with minimal external ponents. 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 500m A of output current while switching at 2.25MHz, allowing the use of small surface mount inductors and capacitors. A modeselect pin allows Burst Mode operation to be enabled for higher efficiency at light...