SLVUDU7 April   2026

 

  1.   1
  2.   Description
  3.   Get Started
  4.   Features
  5.   Applications
  6.   6
  7. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specifications
    4. 1.4 Device Information
      1. 1.4.1 Application Circuit Diagram
  8. 2Hardware
    1. 2.1 Test Setup and Procedure
      1. 2.1.1 EVM Connections
      2. 2.1.2 Test Equipment
      3. 2.1.3 Recommended Test Setup
        1. 2.1.3.1 Input Connections
        2. 2.1.3.2 Output Connections
      4. 2.1.4 Test Procedure
        1. 2.1.4.1 Line and Load Regulation, Efficiency
  9. 3Implementation Results
    1. 3.1 Test Data and Performance Curves
      1. 3.1.1 Efficiency
      2. 3.1.2 Thermal Performance
      3. 3.1.3 Operating Waveforms
        1. 3.1.3.1 Load Transient Response
        2. 3.1.3.2 Start-Up With VIN
        3. 3.1.3.3 Start-Up and Shutdown With ENABLE On and Off
        4. 3.1.3.4 Switching Operation
  10. 4Hardware Design Files
    1. 4.1 Schematic
    2. 4.2 PCB Layout
      1. 4.2.1 Component Drawings
      2. 4.2.2 Layout Guidelines
        1. 4.2.2.1 Power Stage Layout
        2. 4.2.2.2 Small-signal Component Layout
        3. 4.2.2.3 Thermal Design and Layout
        4. 4.2.2.4 Ground Plane Design
    3. 4.3 Bill of Materials
  11. 5Compliance Information
    1. 5.1 Compliance and Certifications
  12. 6Additional Information
    1. 6.1 Trademarks
  13. 7Device and Documentation Support
    1. 7.1 Device Support
      1. 7.1.1 Development Support
    2. 7.2 Documentation Support
      1. 7.2.1 Related Documentation
        1. 7.2.1.1 Low-EMI Design Resources
        2. 7.2.1.2 Thermal Design Resources
        3. 7.2.1.3 PCB Layout Resources

4.2.2.3 Thermal Design and Layout

For a DC/DC converter to be useful over a particular temperature range, the package must allow for the efficient removal of the heat produced while keeping the junction temperature within rated limits. The LMG708B0 converter is available in a small 4.5mm × 6mm, 22-pin, thermally enhanced package (TEP) to cover a range of application requirements.

The useful operating temperature range of a buck converter with integrated GaN FETs, gate drivers and bias supply subregulator is greatly affected by the following:

  • Thermal characteristics of the package and operating environment
  • Factors affecting power FET dissipation
    • Input voltage
    • Output current
    • Switching frequency
  • BIAS pin supply (from the output voltage or an available external supply)

The TEP offers a means of removing heat from the semiconductor die through the exposed thermal pads at the base and top of the package. This removal of heat allows a significant improvement in heatsinking, and the PCB designed with thermal lands, thermal vias, and one or more ground planes to complete the heat removal subsystem becomes imperative. The exposed pads at the base of the LMG708B0 are soldered to the ground-connected copper land on the PCB directly underneath the device package, reducing the IC thermal resistance to a very low value.

Preferably, use a six-layer board with 2oz copper thickness for all layers to provide low impedance, proper shielding and lower thermal resistance. Numerous vias with a 0.3mm diameter connected from the thermal lands (and from the area around the PGND pins) to the internal and solder-side ground planes are vital to facilitate heat transfer. In a multilayer PCB design, place a solid ground plane on the PCB layer below the power-stage components. This plane allows the power-stage currents to flow and also represents a thermally conductive path away from the heat-generating devices.