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The LM2598 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 1-A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5 V, 12 V, and an adjustable output version.

The LM2598 is a member of the LM259x family.

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 required with lower-frequency switching regulators. Available in a standard 7-lead TO-220 package with several different lead bend options, and a 7-lead DDPAK surface mount package. Typically, for output voltages less than 12 V, 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. This feature greatly simplifies the design of switch-mode power supplies.

Other features include a specified ±4% tolerance on output voltage under all conditions of input voltage and output load conditions, and ±15% on the oscillator frequency. External shutdown is included, featuring typically 85-µA standby current. Self-protection features include a two stage current limit for the output switch and an overtemperature shutdown for complete protection under fault conditions.