SLUP412 February 2022 LMG3522R030-Q1

- 1 Introduction
- 2 Comparing Different Technologies
- 3 Advantages of Integrating the Driver With GaN FETs
- 4 The GaN-Based 6.6-kW OBC Reference Design
- 5 PFC Stage
- 6 DC/DC Stage
- 7 DC/DC Topology Selection
- 8 Frequency Selection
- 9 Core Loss
- 10Loss of ZVS
- 11Dead Time
- 12ISR Bandwidth
- 13Overall
- 14Resonant Tank Design
- 15Thermal Solution
- 16Layout Best Practices
- 17Control-Loop Considerations
- 18Conclusions
- 19References
- 20Important Notice

Controlling transformer core loss is a priority, especially high-frequency transformers. Equation 2, the Steinmetz equation, shows the relationship between loss density in the core and frequency:

Equation 2.
${P}_{FE}=k{f}^{\alpha}{B}_{PK}^{\beta}$

where *P _{FE}* is the
loss per unit volume; ƒ is the excitation frequency;

From Equation 2, it is apparent that as the frequency increases, so will the losses. The losses in modern magnetic materials start to become difficult to manage when the switching frequency goes much above 1 or 2 MHz.