The LT1939 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. Cycle-by-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.ApplicationsAutomotive Battery RegulationIndustrial ControlWall Transformer RegulationDistributed Power Regulation