STDA011 September   2025 UCC25661

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Benefits of GaN In LLC Resonant Converter
    1. 2.1 Higher Efficiency
    2. 2.2 Faster Switching Speeds
    3. 2.3 Reduced Parasitic Capacitances
    4. 2.4 Improved Power Density
    5. 2.5 High Thermal Conductivity
    6. 2.6 Lower Junction Temperatures
  6. 3LLC Resonant Converter
    1. 3.1 The Relationship Between Output Voltage (VOUT) and Switching Frequency (fS) in an LLC Resonant Controller
      1. 3.1.1 The LLC Charging Challenge
      2. 3.1.2 A Wide VIN/VOUT Capable LLC
  7. 4Practical Application of LLC Converters for a Battery Charger Leveraging GaN Switches
    1. 4.1 Requirements and Scope
    2. 4.2 Charging Curve for Lithium-Ion Battery
    3. 4.3 How to Support Wide VOUT Range in an LLC Design for Battery Chargers
    4. 4.4 The Prototype Hardware
  8. 5Summary

5 Summary

The LLC resonant topology is known as a highly efficiency topology. For battery charging applications, IPPC enabled LLC controllers like the new family UCC25661 coupled with TI GaN FETs can achieve the highest efficiency and the best overall power density for battery charging applications. UCC25661 is a family of five versions: UCC256610, UCC256611, UCC256612, UCC256613, and UCC256614.

With the new reference design (PMP31393), built with UCC256611 and TI GaN FETs, a design with very low switching and conduction losses is presented. The LLC controller combined with GaN FETs deliver high thermal conductivity, allowing for more compact designs with high power density and low operating temperature. There is no need for advanced cooling, and offer an improved overall system reliability. This is critical parameter to fulfill for battery chargers that will operate in high environment temperatures.