Patent ID: 7391626

Claim:
A chop-wave control circuit to be used on a forward transformation circuit which includes a power driving unit, a transformer, a main output unit and at least one auxiliary output unit; the power driving unit sending power through the transformer to the main output unit and the auxiliary output unit, the main output unit generating a first sync signal and a second sync signal through a self-excited driving unit to control respectively a main output switch and a main flywheel switch that are set on alternately to perform output, the auxiliary output unit including an auxiliary output switch synchronous with the main output switch and an auxiliary flywheel switch and a chop-wave switch that are controlled by the chop-wave control circuit, the chop-wave control circuit comprising: a feedback unit which captures a feedback signal from the auxiliary output unit to generate a slope regulation signal; a ramp generation unit which receives the second sync signal to generate an output cycle range for the ramp generation unit and output a trigger signal which has a triangular wave and alter the slope of the triangular wave according to the slope regulation signal, and perform regulation according to the alteration of the slope of the triangular wave; a latchup unit which receives the trigger signal to alter latchup conditions and set the auxiliary flywheel switch ON or OFF; and a voltage transformation unit which detects potential variations of the latchup unit and determines the latchup conditions of the latchup unit to output or stop a chop-wave signal to set the chop-wave switch ON or OFF; wherein the slope regulation signal alters the slope of the triangular wave of the trigger signal to change trigger time of the latchup unit thereby to alter conduction timing of the auxiliary flywheel switch and the chop-wave switch to match actions of the auxiliary output switch to form a power output cycle of the auxiliary output unit.