Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller

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.

Applications

* Automotive Battery Regulation

* Industrial Control

* Wall Transformer Regulation

* Distributed Power Regulation

* 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