ZHCSNR6G June   1999  – March 2023 LM2576 , LM2576HV

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics: 3.3 V
    6. 6.6  Electrical Characteristics: 5 V
    7. 6.7  Electrical Characteristics: 12 V
    8. 6.8  Electrical Characteristics: 15 V
    9. 6.9  Electrical Characteristics: Adjustable Output Voltage
    10. 6.10 Electrical Characteristics: All Output Voltage Versions
    11. 6.11 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Undervoltage Lockout
      2. 7.3.2 Delayed Start-Up
      3. 7.3.3 Adjustable Output, Low-Ripple Power Supply
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 Current Limit
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Input Capacitor (CIN)
      2. 8.1.2  Inductor Selection
      3. 8.1.3  Inductor Ripple Current
      4. 8.1.4  Output Capacitor
      5. 8.1.5  Catch Diode
      6. 8.1.6  Output Voltage Ripple and Transients
      7. 8.1.7  Feedback Connection
      8. 8.1.8  ON /OFF INPUT
      9. 8.1.9  Inverting Regulator
      10. 8.1.10 Negative Boost Regulator
    2. 8.2 Typical Applications
      1. 8.2.1 Fixed Output Voltage Version
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design with WEBENCH® Tools
          2. 8.2.1.2.2 Inductor Selection (L1)
          3. 8.2.1.2.3 Output Capacitor Selection (COUT)
          4. 8.2.1.2.4 Catch Diode Selection (D1)
          5. 8.2.1.2.5 Input Capacitor (CIN)
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Adjusted Output Voltage Version
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Programming Output Voltage
          2. 8.2.2.2.2 Inductor Selection (L1)
          3. 8.2.2.2.3 Output Capacitor Selection (COUT)
          4. 8.2.2.2.4 Catch Diode Selection (D1)
          5. 8.2.2.2.5 Input Capacitor (CIN)
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
      3. 8.4.3 Grounding
      4. 8.4.4 Heat Sink and Thermal Considerations
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
        1. 9.1.1.1 Definition of Terms
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design with WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 支持资源
    4. 9.4 接收文档更新通知
    5. 9.5 Trademarks
    6. 9.6 静电放电警告
    7. 9.7 术语表
  10. 10Mechanical, Packaging, and Orderable Information

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • NDH|5
  • NEB|5
  • KTT|5
  • KC|5
散热焊盘机械数据 (封装 | 引脚)
订购信息

8.4.4 Heat Sink and Thermal Considerations

In many cases, only a small heat sink is required to keep the LM2576 junction temperature within the allowed operating range. For each application, to determine whether or not a heat sink is required, the following must be identified:

  1. Maximum ambient temperature (in the application).
  2. Maximum regulator power dissipation (in application).
  3. Maximum allowed junction temperature (125°C for the LM2576). For a safe, conservative design, a temperature approximately 15°C cooler than the maximum temperatures must be selected.
  4. LM2576 package thermal resistances θJA and θJC.

Total power dissipated by the LM2576 can be estimated in Equation 11:

Equation 11. PD = (VIN)(IQ) + (VO/VIN)(ILOAD)(VSAT)

where

  • IQ (quiescent current) and VSAT can be found in Section 6.11 shown previously,
  • VIN is the applied minimum input voltage, VO is the regulated output voltage,
  • and ILOAD is the load current.

The dynamic losses during turnon and turnoff are negligible if a Schottky type catch diode is used.

When no heat sink is used, the junction temperature rise can be determined by Equation 12:

Equation 12. ΔTJ = (PD) (θJA)

To arrive at the actual operating junction temperature, add the junction temperature rise to the maximum ambient temperature.

Equation 13. TJ = ΔTJ + TA

If the actual operating junction temperature is greater than the selected safe operating junction temperature determined in step 3, then a heat sink is required.

When using a heat sink, the junction temperature rise can be determined by Equation 13:

Equation 14. ΔTJ = (PD) (θJC + θinterface + θHeat sink)

The operating junction temperature is:

Equation 15. TJ = TA + ΔTJ

As in Equation 15, if the actual operating junction temperature is greater than the selected safe operating junction temperature, then a larger heat sink is required (one that has a lower thermal resistance).