SNOSDI2 March   2024 LMG3425R050

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Pin Configuration and Functions
  6. 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. 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 Slew Rate
      4. 6.1.4 Turn-On and Turn-Off Switching Energy
    2. 6.2 Safe Operation Area (SOA)
      1. 6.2.1 Repetitive SOA
  8. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  GaN FET Operation Definitions
      2. 7.3.2  Direct-Drive GaN Architecture
      3. 7.3.3  Drain-Source Voltage Capability
      4. 7.3.4  Internal Buck-Boost DC-DC Converter
      5. 7.3.5  VDD Bias Supply
      6. 7.3.6  Auxiliary LDO
      7. 7.3.7  Fault Protection
        1. 7.3.7.1 Overcurrent Protection and Short-Circuit Protection
        2. 7.3.7.2 Overtemperature Shutdown Protection
        3. 7.3.7.3 UVLO Protection
        4. 7.3.7.4 High-Impedance RDRV Pin Protection
        5. 7.3.7.5 Fault Reporting
      8. 7.3.8  Drive-Strength Adjustment
      9. 7.3.9  Temperature-Sensing Output
      10. 7.3.10 Ideal-Diode Mode Operation
        1. 7.3.10.1 Operational Ideal-Diode Mode
        2. 7.3.10.2 Overtemperature-Shutdown Ideal-Diode Mode
    4. 7.4 Start-Up Sequence
    5. 7.5 Device Functional Modes
  9. 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 Slew Rate Selection
        2. 8.2.2.2 Signal Level-Shifting
        3. 8.2.2.3 Buck-Boost Converter Design
      3. 8.2.3 Application Curves
    3. 8.3 Do's and Don'ts
    4. 8.4 Power Supply Recommendations
      1. 8.4.1 Using an Isolated Power Supply
      2. 8.4.2 Using a Bootstrap Diode
        1. 8.4.2.1 Diode Selection
        2. 8.4.2.2 Managing the Bootstrap Voltage
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Solder-Joint Reliability
        2. 8.5.1.2 Power-Loop Inductance
        3. 8.5.1.3 Signal-Ground Connection
        4. 8.5.1.4 Bypass Capacitors
        5. 8.5.1.5 Switch-Node Capacitance
        6. 8.5.1.6 Signal Integrity
        7. 8.5.1.7 High-Voltage Spacing
        8. 8.5.1.8 Thermal Recommendations
      2. 8.5.2 Layout Examples
  10. Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Export Control Notice
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

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  • RQZ|54
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発注情報

Signal Level-Shifting

In half-bridges, high-voltage level shifters or digital isolators must be used to provide isolation for signal paths between the high-side device and control circuit. Using an isolator is optional for the low-side device. However, using and isolator equalizes the propagation delays between the high-side and low-side signal paths, and provides the ability to use different grounds for the GaN device and the controller. If an isolator is not used on the low-side device, the control ground and the power ground must be connected at the device and nowhere else on the board. For more information, see Layout Guidelines. With fast-switching devices, common ground inductance can easily cause noise issues without the use of an isolator.

Choosing a digital isolator for level-shifting is important for improvement of noise immunity. As GaN device can easily create high dv/dt, > 50V/ns, in hard-switching applications, TI highly recommends to use isolators with high common-mode transient immunity (CMTI) and low barrier capacitance. Isolators with low CMTI can easily generate false signals, which could cause shoot-through. The barrier capacitance is part of the isolation capacitance between the signal ground and power ground, which is in direct proportion to the common mode current and EMI emission generated during the switching. Additionally, TI strongly encourages to select isolators which are not edge-triggered. In an edge-triggered isolator, a high dv/dt event can cause the isolator to flip states and cause circuit malfunction.

Generally, ON/OFF keyed isolators with default output low are preferred, such as the TI ISO77xxF or ISO67xxF series. Default low state ensures the system will not shoot-through when starting up or recovering from fault events. As a high CMTI event would only cause a very short (a few nanoseconds) false pulse, TI recommends a low pass filter, like 300Ω and 22pF R-C filter, to be placed at the driver input to filter out these false pulses.