SNVS125D March   1998  – May 2016 LM2598

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics - 3.3-V Version
    6. 7.6  Electrical Characteristics - 5-V Version
    7. 7.7  Electrical Characteristics - 12-V Version
    8. 7.8  Electrical Characteristics - Adjustable Voltage Version
    9. 7.9  Electrical Characteristics - All Output Voltage Versions
    10. 7.10 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 SHUTDOWN and Soft-Start
      2. 8.3.2 Inverting Regulator
      3. 8.3.3 Undervoltage Lockout
      4. 8.3.4 Negative Voltage Charge Pump
    4. 8.4 Device Functional Modes
      1. 8.4.1 Discontinuous Mode Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Soft-Start Capacitor (CSS)
      2. 9.1.2 Delay Capacitor (CDELAY)
      3. 9.1.3 Feedforward Capacitor (CFF)
      4. 9.1.4 Input Capacitor (CIN)
      5. 9.1.5 Output Capacitor (COUT)
      6. 9.1.6 Catch Diode
      7. 9.1.7 Inductor Selection
      8. 9.1.8 Output Voltage Ripple and Transients
      9. 9.1.9 Open Core Inductors
    2. 9.2 Typical Application
      1. 9.2.1 LM2598 Fixed Output Series Buck Regulator
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Inductor Selection (L1)
          2. 9.2.1.2.2 Output Capacitor Selection (COUT)
          3. 9.2.1.2.3 Catch Diode Selection (D1)
          4. 9.2.1.2.4 Input Capacitor (CIN)
        3. 9.2.1.3 Application Curves
      2. 9.2.2 LM2598 Adjustable Output Series Buck Regulator
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Programming Output Voltage
          2. 9.2.2.2.2 Inductor Selection (L1)
          3. 9.2.2.2.3 Output Capacitor Selection (COUT)
          4. 9.2.2.2.4 Feedforward Capacitor (CFF)
          5. 9.2.2.2.5 Catch Diode Selection (D1)
          6. 9.2.2.2.6 Input Capacitor (CIN)
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Community Resources
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

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, IQ, 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.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2598 TO-220 (7) 14.986 mm × 10.16 mm
TO-263 (7) 10.10 mm × 8.89 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

LM2598 01259301.png
Fixed output voltage versions