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 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 DDPAK 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 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 85μA standby current. Self protection features include a two stage current limit for the output switch and an over temperature shutdown for complete protection under fault conditions. † Patent Number 5,382,918

• 3.3V, 5V, 12V, and Adjustable Output Versions
• Adjustable Version Output Voltage Range, 1.2V to 37V ±4% Max Over Line and Load Conditions
• Ensured 1A Output Current
• Available in 7-Pin TO-220 and DDPAK (Surface Mount) Package
• Input Voltage Range Up to 40V
• Excellent Line and Load Regulation Specifications
• 150 kHz Fixed Frequency Internal Oscillator
• Shutdown /Soft-start
• Out of Regulation Error Flag
• Error Output Delay
• Low Power Standby Mode, IQ Typically 85μA
• High Efficiency
• Uses Readily Available Standard Inductors
• Thermal Shutdown and Current Limit Protection