National LM2598 Manual
User Manual
The LM2598 series is a monolithic integrated circuit that provides all the active functions for a step-down (buck) switching regulator, capable of driving a 1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, and an adjustable output version. This series of switching regulators is similar to the LM2595 series, with additional supervisory and performance features added. Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation, improved line and load specifications, fixed-frequency oscillator, Shutdown /Soft-start, error flag delay and error flag output. The LM2598 series operates at a switching frequency of 150 kHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Available in a standard 7-lead TO-220 package with several different lead bend options, and a 7-lead TO-263 surface mount package. Typically, for output voltages less than 12V, and ambient temperatures less than 50˚C, no heat sink is required. A standard series of inductors (both through hole and surface mount types) are available from several different manufacturers optimized for use with the LM2598 series. This feature greatly simplifies the design.