1 Features

• 3.3-V, 5-V, 12-V, and Adjustable Output Versions
• Adjustable Version Output Voltage Range, 1.2-V to 37-V ±4% Max Over Line and Load Conditions
• 1-A Output Current
• Available in 7-Pin TO-220 and DDPAK (Surface Mount) Package
• Input Voltage Range Up to 40 V
• 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, I_Q, Typically 85 μA
• High Efficiency
• Uses Readily Available Standard Inductors
• Thermal Shutdown and Current Limit Protection

2 Applications

• Simple High-Efficiency Step-down (Buck) Regulator
• Efficient Preregulator for Linear Regulators
• On-Card Switching Regulators
• Positive to Negative Converter

3 Description

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.

1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

Fixed output voltage versions