Design and Performance of a Resonant LLC 48V Voltage Regulator Module with a Self-sustained Oscillation Controller

This paper presents the performance and design of a new 48V/1.5V Voltage Regulator Module (VRM) for the stand-alone high-end servers, and notebook computer applications. The proposed VRM is based on the LLC-type resonant converter as it possesses much lower component stresses compared with the conventional series and series-parallel resonant topologies. Self-sustained oscillation control (SSOC) operation is used to achieve voltage regulation and high efficiency for a wide range of load currents. It is a new current mode controller for resonant converter, hence offers lower power component ratings than with the conventional variable frequency (VF) controller and a very fast transient response. It allows a minimum power factor angle and consequently a smaller primary current to reduce conduction losses, leading to a better working efficiency. Analytical, simulation and experimental results of a 48V/1.5V 30W prototype are presented to offer the proof of concept.