A High-Frequency LCLC Network Based Resonant DC-DC Converter for Automotive LED Driver Applications

This paper introduces a high-frequency resonant dc-dc converter that inherently achieves a load independent output current while maintaining high efficiency across a wide output voltage range. These properties make the proposed converter well-suited for automotive LED driver applications, where a varying number of LEDs need to be driven with a constant current. The proposed converter achieves load independent output current by utilizing an LCLC resonant network, and achieves high efficiency using a comprehensive design optimization methodology. This LCLC resonant converter is also capable of regulating its output current at any desired value by utilizing phase shift control. A prototype 2-MHz LCLC resonant converter designed for an input voltage of 14 V, an output voltage range of 3 V to 50 V (corresponding to a string of 1 to 15 LEDs), and a constant 0.5 A output current is built and tested. The LCLC resonant converter prototype achieves a peak power stage efficiency of 91.8% and maintains an average efficiency of 89.2% over its output voltage range.