Apparatus and method for generating voltage for driving cathrode ray tube

A CRT driving voltage generating apparatus which can be realized and integrated at low cost, and can prevent breakdown and malfunction of circuits by actively adapting to a change in the frequency of a horizontal synchronous signal, and a CRT driving voltage generating method performed by the apparatus are provided. In this apparatus, a first comparator compares a reference value with the peak value of a fly back pulse. A stability controller shifts the level of the result of the comparison using a current mirroring technique and outputs a compared signal having a shifted level. A second comparator compares the compared signal with a sensing signal to obtain a reset signal. A pulse width modulated signal generator outputs a pulse width modulated signal having a level which is determined in response to the logic levels of a clock signal and a reset signal. A driving voltage generator generates the CRT driving voltage in response to the pulse width modulated signal. A voltage sensor senses the level of the CRT driving voltage to generate the sensing signal. A horizontal output unit generates the fly back pulse having an amplitude which is determined in response to the frequency of a horizontal output signal and the level of the CRT driving voltage.