CIRCUIT FOR DRIVING PIEZOELECTRIC TRANSFORMER

摘要

A circuit for driving a piezoelectric transformer adapted for generating a drive pulse of high frequency-resolution from a low-frequency clock and capable of being digitally processed by carrying out voltage detection by means of a low-cost structure, comprising an error voltage calculating circuit (7) for multiplying the difference between the output data of an A/D converter and the reference data given externally by a constant and outputting the product as error data, a frequency setting circuit (8) for setting the frequency of the drive pulse for driving the piezoelectric transformer as M-bit data based on the error data, and a frequency-division ratio dispersion frequency-dividing circuit (9) for dividing the frequency of a clock of predetermined frequency and generating the drive pulse, wherein the frequency-division ratio of the frequency-division ratio dispersion frequency-dividing circuit is dispersed by the time equal to N periods (N is an integer) of the drive pulse, and the average frequency-division ratio over the N periods is substantially equal to the quotient of the M-bit data divided by N.