Series-parallel resonant forward inverter as a cold cathode fluorescent lamp (CCFL) driver

A square wave, produced by two switches that operate complementarily, is applied to a series-parallel resonant forward inverter, which is composed of leakage inductors, a magnetizing inductor, an external series capacitor and the parasitic parallel capacitor, and filtered into a sinusoid waveform to drive a cold cathode fluorescent lamp (CCFL). The complete operation principle and characteristics of this resonant circuit are discussed in detail in this paper. Complete hardware implementation with the UCC3975 controller and system efficiency are presented too.