SNVS119D March   1998  – May 2016 LM2597 , LM2597HV

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
    6. 7.6  Electrical Characteristics - 5 V
    7. 7.7  Electrical Characteristics - 12 V
    8. 7.8  Electrical Characteristics - Adjustable
    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 Bias Supply Feature
      2. 8.3.2 SHUTDOWN and Soft-Start
      3. 8.3.3 Inverting Regulator
      4. 8.3.4 Undervoltage Lockout
      5. 8.3.5 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
        1. 9.1.2.1 RPULLUP
      3. 9.1.3 Input Capacitor, CIN
      4. 9.1.4 Output Capacitor, COUT
      5. 9.1.5 Catch Diode
      6. 9.1.6 Inductor Selection
      7. 9.1.7 Output Voltage Ripple and Transients
      8. 9.1.8 Open Core Inductors
    2. 9.2 Typical Applications
      1. 9.2.1 Series Buck Regulator (Fixed Output)
        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 Series Buck Regulator (Adjustable Output)
        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 Example
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 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 (57 V for HV Version) ±4% Maximum Over Line and Load Conditions
  • Specified 0.5-A Output Current
  • Available in 8-Pin Surface-Mount and 8-Pin PDIP Packages
  • Input Voltage Range Up to 60 V
  • 150-kHz Fixed-Frequency Internal Oscillator
  • Shutdown/Soft-Start
  • Out of Regulation Error Flag
  • Error Output Delay
  • Bias Supply Pin (VBS) for Internal Circuitry Improves Efficiency at High Input Voltages
  • 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 LM2597xx series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 0.5-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, and are packaged in an 8-pin PDIP and an 8-pin surface-mount package.

This series of switching regulators is similar to the LM2594 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 LM2597xx 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. Because of its high efficiency, the copper traces on the printed-circuit board are normally the only heat sinking required.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2597, LM2597HV SOIC (8) 4.90 mm × 3.91 mm
PDIP (8) 9.81 mm × 6.35 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

LM2597 LM2597HV 01244001.png
Fixed Output Voltage Versions