SNVS124E November   1999  – February 2020 LM2596

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Application
  4. Revision History
  5. Description (continued)
  6. Pin Configuration and Functions
    1.     Pin Functions
  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. 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. 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

Output Capacitor Selection (COUT)

  1. In the majority of applications, low ESR (Equivalent Series Resistance) electrolytic capacitors between 82 μF and 820 μF and low ESR solid tantalum capacitors between 10 μF and 470 μF provide the best results. This capacitor must be placed close to the IC using short capacitor leads and short copper traces. Do not use capacitors larger than 820 μF .
  2. NOTE

    For additional information, see section on output capacitors in Table 3.

  3. To simplify the capacitor selection procedure, see Table 3 for quick design component selection. This table contains different input voltages, output voltages, and load currents, and lists various inductors and output capacitors that will provide the best design solutions.
  4. From Table 3, locate the 5-V output voltage section. In the load current column, choose the load current line that is closest to the current required for the application; for this example, use the 3-A line. In the maximum input voltage column, select the line that covers the input voltage required for the application; in this example, use the 15-V line. The rest of the line shows recommended inductors and capacitors that will provide the best overall performance.

    Table 3. LM2596 Fixed Voltage Quick Design Component Selection Table

    CONDITIONS INDUCTOR OUTPUT CAPACITOR
    THROUGH-HOLE ELECTROLYTIC SURFACE-MOUNT TANTALUM
    OUTPUT
    VOLTAGE
    (V)
    LOAD
    CURRENT
    (A)
    MAX INPUT
    VOLTAGE
    (V)
    INDUCTANCE
    (μH)
    INDUCTOR
    (#)
    PANASONIC
    HFQ SERIES
    (μF/V)
    NICHICON
    PL SERIES
    (μF/V)
    AVX TPS
    SERIES
    (μF/V)
    SPRAGUE
    595D SERIES
    (μF/V)
    3.3 3 5 22 L41 470/25 560/16 330/6.3 390/6.3
    7 22 L41 560/35 560/35 330/6.3 390/6.3
    10 22 L41 680/35 680/35 330/6.3 390/6.3
    40 33 L40 560/35 470/35 330/6.3 390/6.3
    6 22 L33 470/25 470/35 330/6.3 390/6.3
    2 10 33 L32 330/35 330/35 330/6.3 390/6.3
    40 47 L39 330/35 270/50 220/10 330/10
    5 3 8 22 L41 470/25 560/16 220/10 330/10
    10 22 L41 560/25 560/25 220/10 330/10
    15 33 L40 330/35 330/35 220/10 330/10
    40 47 L39 330/35 270/35 220/10 330/10
    9 22 L33 470/25 560/16 220/10 330/10
    2 20 68 L38 180/35 180/35 100/10 270/10
    40 68 L38 180/35 180/35 100/10 270/10
    12 3 15 22 L41 470/25 470/25 100/16 180/16
    18 33 L40 330/25 330/25 100/16 180/16
    30 68 L44 180/25 180/25 100/16 120/20
    40 68 L44 180/35 180/35 100/16 120/20
    15 33 L32 330/25 330/25 100/16 180/16
    2 20 68 L38 180/25 180/25 100/16 120/20
    40 150 L42 82/25 82/25 68/20 68/25

    The capacitor list contains both through-hole electrolytic and surface-mount tantalum capacitors from four different capacitor manufacturers. TI recommends that both the manufacturers and the manufacturer's series that are listed in Table 3.

    In this example aluminum electrolytic capacitors from several different manufacturers are available with the range of ESR numbers required.

    • 330-μF, 35-V Panasonic HFQ Series
    • 330-μF, 35-V Nichicon PL Series

  5. The capacitor voltage rating for electrolytic capacitors should be at least 1.5 times greater than the output voltage, and often require much higher voltage ratings to satisfy the low ESR requirements for low output ripple voltage.
  6. For a 5-V output, a capacitor voltage rating of at least 7.5 V is required. But even a low ESR, switching grade, 220-μF, 10-V aluminum electrolytic capacitor would exhibit approximately 225 mΩ of ESR (see Figure 24 for the ESR versus voltage rating). This amount of ESR would result in relatively high output ripple voltage. To reduce the ripple to 1% or less of the output voltage, a capacitor with a higher value or with a higher voltage rating (lower ESR) must be selected. A 16-V or 25-V capacitor will reduce the ripple voltage by approximately half.