JAJSSX2 February   2025 LMG3650R025

ADVANCE INFORMATION  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Device Comparison
  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
    6. 6.6 Switching Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Switching Parameters
      1. 7.1.1 Turn-On Times
      2. 7.1.2 Turn-Off Times
      3. 7.1.3 Drain-Source Turn-On and Turn-off Slew Rate
      4. 7.1.4 Zero-Voltage Detection Times (LMG3656R025 only)
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
      1. 8.2.1 LMG3650R025 Functional Block Diagram
      2. 8.2.2 LMG3651R025 Functional Block Diagram
      3. 8.2.3 LMG3656R025 Functional Block Diagram
      4. 8.2.4 LMG3657R025 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Drive Strength Adjustment
      2. 8.3.2 VDD Supply
      3. 8.3.3 Overcurrent and Short-Circuit Protection
      4. 8.3.4 Overtemperature Protection
      5. 8.3.5 UVLO Protection
      6. 8.3.6 Fault Reporting
      7. 8.3.7 Auxiliary LDO (LMG3651R025 Only)
      8. 8.3.8 Zero-Voltage Detection (ZVD) (LMG3656R025 Only)
      9. 8.3.9 Zero-Current Detection (ZCD) (LMG3657R025 Only)
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Slew Rate Selection
        2. 9.2.2.2 Signal Level-Shifting
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Using an Isolated Power Supply
      2. 9.3.2 Using a Bootstrap Diode
        1. 9.3.2.1 Diode Selection
        2. 9.3.2.2 Managing the Bootstrap Voltage
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
  11. 10Device and Documentation Support
    1. 10.1 ドキュメントの更新通知を受け取る方法
    2. 10.2 サポート・リソース
    3. 10.3 Trademarks
    4. 10.4 静電気放電に関する注意事項
    5. 10.5 用語集
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

9.3.2.2 Managing the Bootstrap Voltage

In a synchronous buck or other converter where the low-side switch occasionally operates in third-quadrant, the bootstrap supply charges through a path that includes the third-quadrant voltage drop of the low-side LMG365xR025 during the dead time as shown in Charging Path for Bootstrap Diode. This third-quadrant drop can be large, which can overcharge the bootstrap supply in certain conditions. The VDD supply of LMG365xR025 must be kept below 28V.

LMG3650R025 LMG3651R025 LMG3656R025 LMG3657R025 Charging Path for Bootstrap DiodeFigure 9-7 Charging Path for Bootstrap Diode

As shown in Suggested Bootstrap Regulation Circuit, the recommended bootstrap supply includes a bootstrap diode, a series resistor, and a 26V TVS or Zener diode in parallel with the VDD bypass capacitor to prevent damaging the high-side LMG365xR025. The series resistor limits the charging current at start-up and when the low-side device is operating in third-quadrant mode. This resistor must be selected to allow sufficient current to power the LMG365xR025 at the desired operating frequency. At 100kHz operation, TI recommends a value of approximately 2Ω. At higher frequencies, this resistor value must be reduced or the resistor omitted entirely to ensure sufficient supply current.

LMG3650R025 LMG3651R025 LMG3656R025 LMG3657R025 Suggested Bootstrap Regulation Circuit Figure 9-8 Suggested Bootstrap Regulation Circuit