Reliability improvement of FB inverter in HID lamp ballast using UniFET™ II MOSFET family

This paper introduces a newly developed UniFET™ II MOSFET family of which the body diode characteristic has been highly improved and presents its effectiveness for the mixed frequency switching inverter leg in the HID lamp ballast. Its reverse recovery time, T_rr of the body diode is 35 nsec and the peak value of reverse current, i_rr is also much smaller than that of the typical MOSFET and even smaller than FRD´s. Therefore, it can ensure the better reliability in the switching inverter applications in which the performance of the MOSFET body diode is significant. In order to verify the validity, an experiment with an 150W HID lamp ballast was implemented and its results and effectiveness are presented in this paper.