DESCRIPTION
The LTC®1433/LTC1434 are monolithic pulse width modulated step-down DC/DC converters. By utilizing current mode switching techniques, they provide excellent AC and DC load and line regulation. Both devices operate at a fixed frequency with the LTC1434 phase-lockable to an external clock signal.
Both devices incorporate two internal P-channel power MOSFETs with a parallel combined resistance of 0.6Ω (at a supply of 10V). The Adaptive Power output stage selectively drives one or both of the switches at frequencies up to 700kHz to reduce switching losses and maintain high efficiencies at low output currents.

FEATURES
■ High Efficiency: Up to 93%
■ Constant Frequency Adaptive PowerTM Operation
■ Input Voltage Range: 3V to 13.5V
■ Internal 0.6Ω Power Switch (VIN = 10V)
■ Low Dropout Operation: 100% Duty Cycle
■ Low-Battery Detector
■ Internal Power-On Reset Timer
■ Current Mode Operation for Excellent Line and Load Transient Response
■ Low Quiescent Current: 470µA
■ Shutdown Mode Draws Only 15µA Supply Current
■ ±1% Reference Accuracy
■ Available in 16- and 20-Lead Narrow SSOP

APPLICATIONS
■ Cellular Telephones
■ Portable Instruments
■ Wireless Modems
■ RF Communications
■ Distributed Power Systems
■ Scanners
■ Battery-Powered Equipment