SNOAA61A October   2020  – February 2021 LMG3422R030 , LMG3422R050 , LMG3425R030 , LMG3425R050

 

  1.   Trademarks
  2. 1Introduction
  3. 2New QFN 12x12 Package
  4. 3Bottom-Side Cooling Configuration and Definition of RθJC/P
    1. 3.1 Definition of RθJC/P for Package Thermal Performance
    2. 3.2 Design Recommendations for Bottom-Side Cooling System
  5. 4Simulation Models and Results
    1. 4.1 Finite Element Models for Thermal Analysis
    2. 4.2 Thermal Simulation Results
  6. 5Experimental Setup and RθJC/P Testing Results
  7. 6Thermal Performance of QFN 12x12 Package on Half-Bridge Evaluation Board
  8. 7Summary
  9. 8References
  10. 9Revision History

1 Introduction

High-voltage (> 600 V) gallium nitride (GaN) high-electron-mobility transistors (HEMTs) are replacing their silicon (Si)-based counterparts in fast-charging adapters, data centers, telecommunications, electric vehicles, and other applications where the need for high-density, high-efficiency power system becomes pressing and prevalent, see GaN drives energy efficiency to the next level. Due to the reduction or removal of lead induced parasitics, surface-mount type packages are more suitable than through-hole types (e.g., TO-247) for GaN HEMT devices to exploit their use in power switching applications. Texas Instruments (TI) has implemented a direct-drive GaN solution by co-packaging a high-voltage GaN transistor and its driver with an integrated protection into one quad flat no-lead (QFN) package, see Direct-drive configuration for GaN devices. The fully released LMG341x product family uses the same QFN 8x8 (i.e., 8-mm x 8-mm footprint) package for devices of 150-, 70-, and 50-mΩ on-resistance, see Gallium nitride (GaN) ICs – Products. Enabled by this surface-mount packaging solution, TI’s GaN transistor with its integrated driver not only eliminates common-source inductance and significantly reduces gate-loop inductance, but also allows the built-in functions of thermal and current protections, see Optimizing GaN performance with an integrated driver. However, the power dissipation capability of these products is limited because of the small exposed thermal pad area and package size. To address the rising need for high power applications such as 4-kW power supply units for server and telecom, a new QFN 12x12 package has been developed for TI’s next-generation integrated GaN power stages (LMG342x). This application report documents the thermal performance of this new package.