Piezoelectric transformer-driving circuit

摘要

A piezoelectric transformer-driving circuit, wherein the output voltage thereof is changed by changing the frequency of a drive pulse signal to control the current flowing through a cold cathode tube, comprising: a current detection circuit; a rectifying circuit; an A/D converter; an error voltage calculation circuit, outputting error data; a peak detection circuit to detect the resonance point of said piezoelectric transformer; a polarity inversion circuit for inverting the polarity of said error data depending on the output data of said peak detection circuit; a frequency setting circuit for setting the frequency of said drive pulse signal of said piezoelectric transformer by adding the output data of said polarity inversion circuit to the previous frequency setting value.