IS02.2 - Using a Microcontroller-Based Hybrid Hysteretic Control (HHC) of an LLC Converter to Solve Transient Response Challenges in Server PSU Applications

The transient response requirement in server power supply designs has increased significantly recently due to higher power consumption and rapid power variation of servers (M-CRPS). The slew rate requirement has also been reported as high as 2.5 A/us based on CRPS spec. It is very challenging for the traditional voltage mode control (VMC) to meet the high transient-response requirement. The hybrid hysteretic control (HHC) is a combination of charge control and slope compensation, and it can be used to solve transient response challenges in an LLC converter. This presentation will go over design challenges and possible solutions of a 1-kw digitally-controlled HHC LLC converter for server power supplies.