SNVS124E November   1999  – February 2020 LM2596

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  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 Delayed Start-Up
      2. 8.3.2 Undervoltage Lockout
      3. 8.3.3 Inverting Regulator
      4. 8.3.4 Inverting Regulator Shutdown Methods
    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 Input Capacitor (CIN)
      2. 9.1.2 Feedforward Capacitor (CFF)
      3. 9.1.3 Output Capacitor (COUT)
      4. 9.1.4 Catch Diode
      5. 9.1.5 Inductor Selection
      6. 9.1.6 Output Voltage Ripple and Transients
      7. 9.1.7 Open-Core Inductors
    2. 9.2 Typical Applications
      1. 9.2.1 LM2596 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 Custom Design with WEBENCH Tools
          2. 9.2.1.2.2 Inductor Selection (L1)
          3. 9.2.1.2.3 Output Capacitor Selection (COUT)
          4. 9.2.1.2.4 Catch Diode Selection (D1)
          5. 9.2.1.2.5 Input Capacitor (CIN)
        3. 9.2.1.3 Application Curves
      2. 9.2.2 LM2596 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 Device Support
      1. 12.1.1 Custom Design with WEBENCH Tools
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • NDH|5
  • NEB|5
  • KTT|5
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.2.2.1 Programming Output Voltage

Select R1 and R2, as shown in Table 6

Use Equation 1 to select the appropriate resistor values.

Equation 1. LM2596 01258348.png

Select a value for R1 between 240 Ω and 1.5 kΩ. The lower resistor values minimize noise pickup in the sensitive feedback pin. (For the lowest temperature coefficient and the best stability with time, use 1% metal film resistors.). Calculate R2 with Equation 2.

Equation 2. LM2596 01258349.png

Select R1 to be 1 kΩ, 1%. Solve for R2 in Equation 3.

Equation 3. LM2596 01258351.png

R2 = 1 k (16.26 − 1) = 15.26 k, closest 1% value is 15.4 kΩ.

R2 = 15.4 kΩ.