Power distribution to the High-Luminosity Large Hadron Collider (HL-LHC)detectors at CERN is a challenging task, due to the limited amount of mate-rial that can be used, to the limited cooling capability and to the presenceof high levels of radiation. In this context, the use of step-down radiationtolerant DC-DC converters is of paramount importance to guarantee that thetargets of power efficiency and minimization of the used material are met. Anew generation of Gallium Nitride (GaN) based converters is now in devel-opment at CERN.During recent years, the employment of GaN devices has become more andmore widespread due their increased switching capabilities and power lossesreduction.