Drive circiut of switching element for switching mode power supply device

摘要

Described is a drive circuit of a switching element for controlling a switching element. The drive circuit of a switching element in the present invention includes a power conversion section for converting an alternating current inputted to a direct current; a switching element for switching the direct current of the power conversion section to load; an oscillator for generating a drive signal having rectangular pulse form with a predetermined cycle according to a control signal inputted from outside; a first control signal generator for generating a first control signal each time a drive signal of an oscillator is triggered from a low level to a high level; a second control signal generator for generating a second control signal each time a control signal inputted from outside is triggered from a high level to a low level; and a drive section for switching the switching element to turn-on state according to a first control signal and for switching the switching element to turn-off state according to a second control signal. As the first control signal is generated periodically and successively, precise switching of the switching element can be achieved even when the cycle of switching is low, and thus reducing the size of a transformer.