DC voltage conversion circuit

摘要

In a fly-back DC voltage conversion circuit, a transformer accumulates energy during the on-state of a switching element, and the accumulated energy is outputted from a secondary winding during the off-state of the switching element. The switching element is placed in the on-state when the accumulated energy is completely outputted from the secondary winding. A voltage applied to the switching element is differentiated by a capacitor to detect a discharge termination point at which the current of the transformer becomes zero to change a switching frequency of the switching element. The DC voltage conversion circuit can attain control in a current boundary state without significantly increasing cost.