DESCRIPTION
The LTC®3448 is a high efficiency, monolithic, synchronous buck regulator using a constant frequency, current mode architecture. Supply current during operation is only 32µA (linear regulator mode) and drops to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3448 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. At moderate output load levels, PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications.

FEATURES
■ High Efficiency: Up to 96%
■ Very Low Quiescent Supply Current: 32µA During
   Linear Regulator Operation
■ 600mA Output Current (Buck Converter)
■ Optionally Operates as Linear Regulator Below
   3mA—External or Automatic ON/OFF
■ 2.5V to 5.5V Input Voltage Range
■ 1.5MHz or 2.25MHz Constant Frequency Operation
   or External Synchronization
■ No Schottky Diode Required
■ Low Dropout Operation: 100% Duty Cycle
■ 0.6V Reference Allows Low Output Voltages
■ Shutdown Mode Draws < 1µA Supply Current
■ Current Mode Operation for Excellent Line and
   Load Transient Response
■ Overtemperature Protected
■ Low Profile (3mm × 3mm) 8-Lead DFN and 8-Lead
   MSOP Packages

APPLICATIONS
■ Cellular Telephones
■ Personal Information Appliances
■ Wireless and DSL Modems
■ Digital Still Cameras
■ MP3 Players
■ Portable Instruments