Digital PFC + Half-bridge/LLC Combo IC

Resonant-mode power supplies are a variation of SMPS circuits offering advantages such as high efficiency, low EMI, and high power density. By applying ZCS (zero-current) and ZVS (zero-voltage) switching schemes, switching losses are reduced significantly. Consequently, these resonant converters are also known as soft-switching controllers. Non-resonant mode SMPS circuits rely on hard-switching techniques. As such, Infineon offers 2 types of resonant-mode controller ICs, namely hybrid flyback (or commonly known as asymmetric half-bridge flyback topology), and LLC controllers.

Both types of resonant controllers share similarities such as utilizing an external capacitor as well as leakage inductance from the main transformer to form a resonant tank to aid its switching operation. Although both types of converters look similar at first glance, distinct differences exist to best fit each targeted application.

Hybrid flyback controllers combine the simplicity of a flyback with the performance of resonant mode. By utilizing two high-voltage MOSFETs such as CoolMOS™, hybrid flyback controllers are able to drive both high-and low-side MOSFET in an asymmetric half-bridge flyback topology. To reduce switching losses, ZVS and ZCS are achieved through the means of regulating both positive and negative magnetizing current. In addition, transformer leakage energy is recycled thereby further reduces switching losses.