SWITCHING POWER SUPPLY DEVICE

摘要

There is provided a switching power supply device having an input voltage level detection circuit for detecting a voltage level between AC input terminals when the AC input of the switching power supply device is cut off and stopping the oscillation operation of a primary control circuit when the level becomes a predetermined level or below. Thus, it is possible to make the DC output voltage upon cut-off of the AC input during light load fall within a predetermined time and to suppress the power consumption during the light load.