This paper presents a digital current controller for zero-current transition (ZCT) converters. In order to reduce switching losses and noises, a soft-switching technique is adopted. It is suitable for the pulse-width modulation (PWM), because the resonant transition is very short and it is independent of the switching frequency. A field programmable gate array (FPGA) and a 2.5MHz analog to digital (A/D) converter can control the inductor current. From the experimental results, the current is controlled precisely even if the duty factor is more than 50%. Also, the zero-current transition operation of the main switch is confirmed and the efficiency of the converter is improved.
