the power converter to change accordingly that is to precipitate the rising slopes of each output voltages of a power converter to approach an unanimity during start up period in this manner the u201c rising slope out of control u201d problem can be settled efficiently referring to fig5 the circuit configuration of a reference voltage generator 212 according to a preferred embodiment of the present invention is comprised of a comparator 301 having an inverting input terminal n 1 for receiving a sensed bulk voltage bsense from a secondary winding of a transformer in which a voltage waveform of bsense signal is demonstrated in fig7 and a non inverting input terminal for receiving a fixed voltage 307 the comparator 301 compares the sensed bulk voltage bsense with the fixed voltage 307 and in response thereto provide a switch control signal vsw for a switch 303 in a circuit for generating linear voltage within a rising slope generating circuit 315 the circuit 315 for generating linear voltage with a rising slope includes switches 303 304 a current source 302 a capacitor cs and a voltage follower 305 the switch 303 switches its on off state in response to a state of the switch signal vsw when the switch 303 is off the current source 302 charges the capacitor cs and stores energy in the capacitor cs when the switch 303 is on the capacitor cs starts to discharge the stored energy to a non inverting input terminal of the voltage follower 305 through a circuit node n 2 under this condition the voltage appearing at a non inverting input terminal of the voltage follower 305 is a.