High-frequency LC³L resonant DC-DC converter for automotive LED driver applications

This paper presents a high-frequency zero-voltage switching (ZVS) resonant converter using a novel LC ³ L resonant tank. The converter behaves like a current source, with its dc output current independent of the output voltage. This property is favorable for LED driver applications, including automotive lighting. Furthermore, the converter exhibits minimal circulating current over its output voltage range. To reduce radio frequency interference, the converter is designed to operate at switching frequency above the AM frequency band. Experimental results are given for a 2 MHz LC ³ L converter prototype operating over an output voltage range of 3 V to 50 V while supplying a constant 0.5 A output current to a string of 1-to-15 LEDs. Using Silicon MOSFETs, the prototype achieves a peak efficiency of 89.5%, and maintains greater than 85% efficiency across a wide output voltage range.