SNOSDL7A January   2025  – December 2025 LMG3650R070

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Switching Parameters
      1. 6.1.1 Turn-On Times
      2. 6.1.2 Turn-Off Times
      3. 6.1.3 Drain-Source Turn-On and Turn-off Slew Rate
      4. 6.1.4 Zero-Voltage Detection Times (LMG3656R070 only)
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
      1. 7.2.1 LMG3650R070 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Drive Strength Adjustment
      2. 7.3.2 VDD Supply
      3. 7.3.3 Overcurrent and Short-Circuit Protection
      4. 7.3.4 Overtemperature Protection
      5. 7.3.5 UVLO Protection
      6. 7.3.6 Fault Reporting
      7. 7.3.7 Auxiliary LDO (LMG3651R070 Only)
      8. 7.3.8 Zero-Voltage Detection (ZVD) (LMG3656R070 Only)
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Slew Rate Selection
        2. 8.2.1.2 Signal Level-Shifting
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Using an Isolated Power Supply
      2. 8.3.2 Using a Bootstrap Diode
        1. 8.3.2.1 Diode Selection
        2. 8.3.2.2 Managing the Bootstrap Voltage
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Solder-Joint Reliability
        2. 8.4.1.2 Power-Loop Inductance
        3. 8.4.1.3 Signal-Ground Connection
        4. 8.4.1.4 Bypass Capacitors
        5. 8.4.1.5 Switch-Node Capacitance
        6. 8.4.1.6 Signal Integrity
        7. 8.4.1.7 High-Voltage Spacing
        8. 8.4.1.8 Thermal Recommendations
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1.     PACKAGE OPTION ADDENDUM
    2. 11.1 Tape and Reel Information
    3. 11.2 Mechanical, Packaging, and Orderable Information

8.3.2.2 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 LMG365xR070 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. Verify that the VDD supply of LMG365xR070 remains below 26V.

LMG3650R070 LMG3651R070 LMG3656R070 LMG3657R070 Charging Path for Bootstrap DiodeFigure 8-7 Charging Path for Bootstrap Diode

As Suggested Bootstrap Regulation Circuit shows, the recommended bootstrap supply includes a bootstrap diode, series resistor, and 24V TVS or Zener diode in parallel with the VDD bypass capacitor. The parallel location prevents damage to the high-side LMG365xR070. The series resistor limits the charging current at start-up and when the low-side device operates in third-quadrant mode. Select the resistor to allow sufficient current to power the LMG365xR070 at the desired operating frequency. At 100kHz operation, TI recommends a value of approximately 2Ω. At higher frequencies, reduce or omit the resistor value to establish sufficient supply current.

LMG3650R070 LMG3651R070 LMG3656R070 LMG3657R070 Suggested Bootstrap Regulation Circuit Figure 8-8 Suggested Bootstrap Regulation Circuit