DESCRIPTION
The LTC®3409 is a high efficiency, monolithic synchronous buck regulator using a constant frequency, current mode architecture. The output voltage is adjusted via an external resistor divider.
Fixed switching frequencies of 1.7MHz and 2.6MHz are supported. Alternatively, an internal PLL will synchronize to an external clock in the frequency range of 1MHz to 3MHz. This range of switching frequencies allows the use of small surface mount inductors and capacitors, including ceramics.

FEATURES
■ 1.6V to 5.5V Input Voltage Range
■ Internal Soft-Start
■ Selectable 1.7MHz or 2.6MHz Constant Frequency
   Operation
■ Internal Oscillator can be Synchronizable to an
   External Clock, 1MHz to 3MHz Range
■ High Efficiency: Up to 95%
■ Very Low Quiescent Current: Only 65µA During
   Burst Mode® Operation
■ 600mA Output Current (VIN = 1.8V, VOUT = 1.2V)
■ 750mA Peak Inductor Current
■ No Schottky Diode Required
■ Low Dropout Operation: 100% Duty Cycle
■ 0.613V Reference Voltage
■ Stable with Ceramic Capacitors
■ Shutdown Mode Draws <1µA Supply Current
■ Current Mode Operation for Excellent Line and Load
   Transient Response
■ Overtemperature Protection
■ Available in a Low Profile (0.75mm) 8-Lead
   (3mm × 3mm) DFN Package

APPLICATIONS
■ Cellular Phones
■ Digital Cameras
■ MP3 Players