SLUAAP2 March   2023 LMG2610 , UCC28782

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Design Requirement 1: Managing Thermals Induced by Power Losses
    2. 1.2 Design Requirement 2: Reducing Energy Storage Requirement by Switching at High Frequency
  4. 2A Brief Introduction to GaN's Value
  5. 3The Active Clamp Flyback
    1. 3.1 Power Loss Saving 1: Zero-Clamp Loss
    2. 3.2 Power Loss Saving 2: Zero-Voltage-Switching
  6. 4The Value of GaN in Active Clamp Flyback
  7. 5Leveraging Integrated GaN to Simplify ACF Stage
  8. 6Physical Design Implementations Using LMG2610 Integrated Half-Bridge and UCC28782 ACF Controller
    1. 6.1 UCC28782EVM-030
    2. 6.2 PMP23146
  9. 7Leverage Design Tools for ACF
  10. 8Summary
  11. 9References

3.1 Power Loss Saving 1: Zero-Clamp Loss

Typically, low-power applications employ a flyback converter for simplicity and cost. Such designs use a flyback transformer with inherent leakage inductance that can cause uncontrolled voltage spikes on the primary FET (Q1). In the ACF, excess energy from the leakage inductance of the transformer,Llk, is stored in the clamp capacitor,Cclamp, through the high-side FET, Q2. This leakage energy is then released to the output, together with the magnetizing inductance energy, through a resonant process. The key benefit here is that the leakage energy can be released to the output instead of being dissipated through a passive clamp. The Cclamp capacitor acts as an active clamp, hence the name active-clamp flyback.