| 摘要 |
The invention provides a power supply device which can provide a sufficiently long ending process time to an electronic equipment connected thereto even if an input voltage is disconnected abnormally and reduces the circuit area and the power consumption. The power supply device includes a switching power supply section for receiving a DC voltage as an input voltage at a primary side thereof, switching the inputted DC voltage and generating a stabilized output DC voltage at a secondary side thereof isolated from the primary side, a current detection section for generating a synchronization pulse synchronized with supply current to the switching power supply section, and a control section for outputting a detection pulse to convey disconnection of an AC input to the switching power supply section to the electronic equipment side based on the synchronization pulse. The current detection section generates the synchronization pulse in an isolated relationship from the primary side of the switching power supply section by means of, for example, a photo-coupler.
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