A low delay time power converter circuit includes a driver circuit and a load. The driver circuit generates a switching driving signal to control the load. The driver circuit includes a switching control circuit and an output stage circuit which includes a first power switch, a second power switch and an impedance adjusting circuit. When the switching control circuit controls the switching driving signal to a first voltage level at a first time point, the first power switch is turned ON and then is turned OFF after a predetermined period. When the switching control circuit controls the switching driving signal to a second voltage level at a second time point, the second power switch is turned ON. The time point when the first power switch is turned OFF is earlier than the second time point. A resistance of the impedance adjusting circuit is larger than a conductive resistance of the first power switch.