ZHCSRY0M april   2000  – may 2023 LM2676

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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: LM2676 – 3.3 V
    6. 6.6  Electrical Characteristics: LM2676 – 5 V
    7. 6.7  Electrical Characteristics: LM2676 – 12 B
    8. 6.8  Electrical Characteristics: LM2676 – Adjustable
    9. 6.9  Electrical Characteristics – All Output Voltage Versions
    10. 6.10 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Switch Output
      2. 7.3.2 Input
      3. 7.3.3 C Boost
      4. 7.3.4 Ground
      5. 7.3.5 Feedback
      6. 7.3.6 ON/OFF
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Design Considerations
      2. 8.1.2 Inductor
      3. 8.1.3 Output Capacitor
      4. 8.1.4 Input Capacitor
      5. 8.1.5 Catch Diode
      6. 8.1.6 Boost Capacitor
      7. 8.1.7 Additional Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application for All Output Voltage Versions
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Capacitor Selection Guides
          2. 8.2.1.2.2 Inductor Selection Guides
      2. 8.2.2 Application Curves
      3. 8.2.3 Fixed Output Voltage Application
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
          1. 8.2.3.2.1 Capacitor Selection
      4. 8.2.4 Adjustable Output Voltage Application
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
          1. 8.2.4.2.1 Capacitor Selection
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 Trademarks
    5. 9.5 静电放电警告
    6. 9.6 术语表
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 DAP (VSON Package)

封装选项

机械数据 (封装 | 引脚)
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订购信息

8.2.1.2 Detailed Design Procedure

A complete step-down regulator can be designed in a few simple steps using the nomographs and tables in this data sheet (or use the available design software at www.ti.com).

Step 1: Define the power supply operating conditions:

  • Required output voltage
  • Maximum DC input voltage
  • Maximum output load current

Step 2: Set the output voltage by selecting a fixed output LM2676 (3.3-V, 5-V or 12-V applications) or determine the required feedback resistors for use with the adjustable LM2676-ADJ.

Step 3: Determine the inductor required by using one of the four nomographs (Figure 8-2 through Figure 8-5). Table 8-3 provides a specific manufacturer and part number for the inductor.

Step 4: Using Table 8-5 and Table 8-6 (fixed output voltage) or Table 8-9 and Table 8-10 (adjustable output voltage), determine the output capacitance required for stable operation. Table 8-1 and Table 8-2 provide the specific capacitor type from the manufacturer of choice.

Step 5: Determine an input capacitor from Table 8-7 or Table 8-8 for fixed output voltage applications. Use Table 8-1 or Table 8-2 to find the specific capacitor type. For adjustable output circuits, select a capacitor from Table 8-1 or Table 8-2 with a sufficient working voltage (WV) rating greater than VIN max, and an RMS current rating greater than one-half the maximum load current (two or more capacitors in parallel can be required).

Step 6: Select a diode from Table 8-4. The current rating of which must be greater than ILOAD max and the reverse voltage rating must be greater than VIN max.

Step 7: Include a 0.01-µF, 50-V capacitor for CBOOST in the design.