DESCRIPTION
The LTC®3543 is a high effi ciency monolithic synchronous current mode buck regulator.
The switching frequency is internally set at 2.25MHz, allowing the use of small surface mount inductors and capacitors. In PLL mode, the LTC3543 can acquire frequencies between 1MHz and 3MHz. Also, the LTC3543 has spread spectrum capability providing a lower noise regulated output, as well as low noise at the input.

FEATURES
■ 600mA Output Current
■ 2.5V to 5.5V Input Voltage Range
■ 2.25MHz Constant Frequency Operation, Spread
   Spectrum or Synchronized PLL (1MHz to 3MHz)
■ High Effi ciency: Up to 95%
■ 1A Peak Inductor Current
■ Very Low Quiescent Current: Only 45µA During
   Burst Mode Operation
■ No Schottky Diode Required
■ Low Dropout Operation: 100% Duty Cycle
■ Overtemperature Protected
■ Stable with Ceramic Capacitors
■ Shutdown Mode Draws <1µA Supply Current
■ ±2% Output Voltage Accuracy
■ Current Mode Operation for Excellent Line and Load
   Transient Response
■ Soft-Start
■ Available in a Low Profi le (0.75mm) 2mm × 3mm
   6-Lead DFN Package

APPLICATIONS
■ Portable Instruments
■ Cellular Phones