JAJSR60F August   2008  – June 2020 TPS40210-Q1 , TPS40211-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5.   5
  6. 4 Revision History
  7. 5 Pin Configuration and Functions
    1.     Pin Functions
  8. 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
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  9. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Minimum On-Time and Off-Time Considerations
      2. 7.3.2  Current Sense and Overcurrent
      3. 7.3.3  Current Sense and Subharmonic Instability
      4. 7.3.4  Current Sense Filtering
      5. 7.3.5  Soft Start
      6. 7.3.6  BP Regulator
      7. 7.3.7  Shutdown (DIS/ EN Pin)
      8. 7.3.8  Control Loop Considerations
      9. 7.3.9  Gate Drive Circuit
      10. 7.3.10 TPS40211-Q1
    4. 7.4 Device Functional Modes
      1. 7.4.1 Setting the Oscillator Frequency
      2. 7.4.2 Synchronizing the Oscillator
  10. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Duty Cycle Estimation
        2. 8.2.2.2  Inductor Selection
        3. 8.2.2.3  Rectifier Diode Selection
        4. 8.2.2.4  Output Capacitor Selection
        5. 8.2.2.5  Input Capacitor Selection
        6. 8.2.2.6  Current Sense and Current Limit
        7. 8.2.2.7  Current Sense Filter
        8. 8.2.2.8  Switching MOSFET Selection
        9. 8.2.2.9  Feedback Divider Resistors
        10. 8.2.2.10 Error Amplifier Compensation
        11. 8.2.2.11 R-C Oscillator
        12. 8.2.2.12 Soft-Start Capacitor
        13. 8.2.2.13 Regulator Bypass
      3. 8.2.3 Application Curves
  11. 9 Power Supply Recommendations
  12. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  13. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 サード・パーティ製品に関する免責事項
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 ドキュメントの更新通知を受け取る方法
    5. 11.5 サポート・リソース
    6. 11.6 Trademarks
    7. 11.7 静電気放電に関する注意事項
    8. 11.8 用語集
  14. 12Mechanical, Packaging, and Orderable Information
    1.     70

8.2.2.3 Rectifier Diode Selection

A low-forward voltage drop Schottky diode is used as a rectifier diode to reduce its power dissipation and improve efficiency. Using 80% derating, on VOUT for ringing on the switch node, the rectifier diode minimum reverse break-down voltage is given by Equation 41.

Equation 41. GUID-1D8EBC6D-245A-4816-A93A-AD315393C3B2-low.gif

The diode must have reverse breakdown voltage greater than 30 V. The rectifier diode peak and average currents are estimated by Equation 42 and Equation 43.

Equation 42. GUID-3DB7E4FA-1B3F-45DE-A07E-82222C82D51D-low.gif
Equation 43. GUID-E56BEFFC-3E4B-4286-A57C-03B780CC13C4-low.gif

For this design, 2-A average and 6.57-A peak is:

The power dissipation in the diode is estimated by Equation 44.

Equation 44. GUID-6725C8F6-6050-4E85-9E16-8995FE39E968-low.gif

For this design, the maximum power dissipation is estimated as 1 W. Reviewing 30-V and 40-V Schottky diodes, the MBRS340T3 40-V 3-A diode in an SMC package is selected. This diode has a forward voltage drop of 0.48 V at 6 A, so the conduction power dissipation is approximately 960 mW, less than half its rated power dissipation.