SNVS007H september   1998  – june 2023 LM2676

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Description (continued)
  7. 6 Pin Configuration and Functions
  8. 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
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Adjustable Output Voltage
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Active Mode
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Fixed Output Voltage Typical Application
        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)
          6. 9.2.1.2.6 Boost Capacitor (CB)
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Adjustable Output Voltage Typical Application
        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 Catch Diode Selection (D1)
          5. 9.2.2.2.5 Input Capacitor (CIN)
          6. 9.2.2.2.6 Boost Capacitor (CB)
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Typical Application for All Output Voltage Versions
        1. 9.2.3.1 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 WSON Package Devices
      2. 9.4.2 Layout Examples
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 Custom Design with WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.1.2.4 Catch Diode Selection (D1)
  1. In normal operation, the average current of the catch diode is the load current times the catch diode duty cycle, 1-D (D is the switch duty cycle, which is approximately the output voltage divided by the input voltage). The largest value of the catch diode average current occurs at the maximum load current and maximum input voltage (minimum D). For normal operation, the catch diode current rating must be at least 1.3 times greater than its maximum average current. However, if the power supply design must withstand a continuous output short, the diode must have a current rating equal to the maximum current limit of the LM2674. The most stressful condition for this diode is a shorted output condition. Refer to Table 9-3. In this example, a 1-A, 20-V Schottky diode provides the best performance. If the circuit must withstand a continuous shorted output, TI recommends a higher current Schottky diode.
    Table 9-3 Schottky Diode Selection Table
    VR 500-mA DIODES 3-A DIODES
    SURFACE MOUNT THROUGH-HOLE SURFACE MOUNT THROUGH-HOLE
    20V SK12 1N5817 SK32 1N5820
    B120 SR102 SR302
    30V SK13 1N5818 SK33 1N5821
    B130 11DQ03 30WQ03F 31DQ03
    MBRS130 SR103
    40V SK14 1N5819 SK34 1N5822
    B140 11DQ04 30BQ040 MBR340
    MBRS140 SR104 30WQ04F 31DQ04
    10BQ040 MBRS340 SR304
    10MQ040 MBRD340
    15MQ040
    50V SK15 MBR150 SK35 MBR350
    B150 11DQ05 30WQ05F 31DQ05
    10BQ050 SR105 SR305
  2. The reverse voltage rating of the diode must be at least 1.25 times the maximum input voltage.
  3. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best performance and efficiency. This Schottky diode must be placed close to the LM2674 using short leads and short printed-circuit traces.