LT1939 Datasheet | Linear Technology

Features n n n n n n n n n n 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 250k Hz to 2.2MHz Soft-Start/Tracking Capability Output Adjustable Down to 0.8V Adjustable Linear Regulator/Driver with 13m A Output Capability Power Good parator with plementary 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 250k Hz to 2.2MHz frequency range and synchronization capability enable optimization between efficiency and external ponent 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. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. APPLICATIONS n n n n Automotive Battery Regulation Industrial Control Wall Transformer Regulation Distributed Power Regulation TYPICAL APPLICATION Dual Step-Down Converters BAT54 VIN 6V TO 25V 2.2μF VIN LT1939 SW SHDN SS 0.47μF FB PG PG RT/SYNC LDRV VC LFB 40.2k 8.06k 22μF 1939 TA01a Switching Converter Efficiency 90 85 VOUT1 5V...