In those conventional arts, a power supply with a voltage holdup circuit generates
a peak voltage in output voltage when a switching operation is occurred, and so
the quality of the output voltage is decreased and a risk of operating fault in
a load apparatus. The present invention employs a feed forward circuit to immediately
generate a forward feedback signal when a switching operation is occurred. Hence,
the output voltage can be faster corrected to a accurate output voltage and so
the peak voltage can be reduced.
