LTC3541 Datasheet | Linear Technology

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 High Efficiency, 500m A Buck (VIN: 2.7V to 5.5V) nn 300m A VLDO Regulator with 30m A Standalone Mode nn No External Schottky Diodes Required nn Buck Output Voltage Range: 0.8V to 5V nn VLDO Input Voltage Range (LVIN): 0.9V to 5.5V nn VLDO Output Voltage Range VLDO: 0.4V to 4.1V nn Selectable Fixed Frequency, Pulse-Skip Operation or nn Burst Mode® Operation nn Short-Circuit Protected nn Current Mode Operation for Excellent Line and Load Transient Response 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 PDAs/Palmtop PCs nn Digital Cameras nn Cellular Phones nn PC Cards nn Wireless and DSL Modems nn Other Portable Power Systems High Efficiency Buck + VLDO Regulator DESCRIPTION The LTC®3541 bines 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 ponents. 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 500m A 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...