LT1939
Overview
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- LT1939 Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller DESCRIPTION Wide Input Range: 3V to 25V Short-Circuit Protected Over Full Input Range 2A Output Current Capability Adjustable/Synchronizable Fixed Frequency Operation from 250kHz to 2.2MHz Soft-Start/Tracking Capability Output Adjustable Down to 0.8V Adjustable Linear Regulator/Driver with 13mA Output Capability Power Good Comparator with Complementary Outputs Low Shutdown Current: 12μA Thermally Enhanced 3mm × 3mm DFN Package The LT®1939 is a current mode PWM step-down DC/DC converter with an internal 2.3A switch. The wide input range of 3V to 25V makes the LT1939 suitable for regulating power from a wide variety of sources, including automotive batteries, industrial supplies and unregulated wall adapters. Resistor-programmable 250kHz to 2.2MHz frequency range and synchronization capability enable optimization between efficiency and external component size. Cycleby-cycle current limit, frequency foldback and thermal shutdown provide protection against a shorted output. The soft-start feature controls the ramp rate of the output voltage, eliminating input current surge during start-up, and also provides output tracking. The LT1939 contains an internal NPN transistor with feedback control which can be configured as a linear regulator or as a linear regulator controller. The LT1939’s low current shutdown mode (<12μA) enables easy power management in battery-powered systems.
