SNOSDH5 November   2024 LMG2640

PRODUCTION DATA  

  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 GaN Power FET Switching Parameters
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  GaN Power FET Switching Capability
      2. 7.3.2  Current-Sense Emulation
      3. 7.3.3  Bootstrap Diode Function
      4. 7.3.4  Input Control Pins (EN, INL, INH)
      5. 7.3.5  INL - INH Interlock
      6. 7.3.6  AUX Supply Pin
        1. 7.3.6.1 AUX Power-On Reset
        2. 7.3.6.2 AUX Under-Voltage Lockout (UVLO)
      7. 7.3.7  BST Supply Pin
        1. 7.3.7.1 BST Power-On Reset
        2. 7.3.7.2 BST Under-Voltage Lockout (UVLO)
      8. 7.3.8  Over-Current Protection
      9. 7.3.9  Over-Temperature Protection
      10. 7.3.10 Fault Reporting
    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 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Solder-Joint Stress Relief
        2. 8.4.1.2 Signal-Ground Connection
        3. 8.4.1.3 CS Pin Signal
      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 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

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発注情報

7.3.1 GaN Power FET Switching Capability

Due to the silicon FET’s long reign as the dominant power-switch technology, many designers are unaware that the nameplate drain-source voltage cannot be used as an equivalent point to compare devices across technologies. The nameplate drain-source voltage of a silicon FET is set by the avalanche breakdown voltage. The nameplate drain-source voltage of a GaN FET is set by the long term compliance to data sheet specifications.

Exceeding the nameplate drain-source voltage of a silicon FET can lead to immediate and permanent damage. Meanwhile, the breakdown voltage of a GaN FET is much higher than the nameplate drain-source voltage. For example, the breakdown drain-source voltage of the LMG2640 GaN power FET is more than 800V which allows the LMG2640 to operate at conditions beyond an identically nameplate rated silicon FET.

The LMG2640 GaN power FET switching capability is explained with the assistance of Figure 7-1. The figure shows the drain-source voltage versus time for the LMG2640 GaN power FET for four distinct switch cycles in a switching application. No claim is made about the switching frequency or duty cycle. The first two cycles show normal operation and the second two cycles show operation during a rare input voltage surge. The LMG2640 GaN power FETs are intended to be turned on in either zero-voltage switching (ZVS) or discontinuous-conduction mode (DCM) switching conditions.


LMG2640 GaN Power FET Switching Capability

Figure 7-1 GaN Power FET Switching Capability

Each cycle starts before t0 with the FET in the on state. At t0 the GaN FET turns off and parasitic elements cause the drain-source voltage to ring at a high frequency. The high frequency ringing has damped out by t1. Between t1 and t2 the FET drain-source voltage is set by the characteristic response of the switching application. The characteristic is shown as a flat line (plateau), but other responses are possible. At t2 the GaN FET is turned on. For normal operation, the transient ring voltage is limited to 650V and the plateau voltage is limited to 520V. For rare surge events, the transient ring voltage is limited to 800V and the plateau voltage is limited to 720V.