Switched-mode power supply using ac-dc conversion having inverted control

摘要

A switched-mode power supply includes a first rectifier circuit configured to generate a first rectified voltage from an AC input voltage. An inverter generates a second AC voltage from the first rectified voltage. A transformer includes a primary coil coupled to the second AC voltage and a secondary coil. A second rectifier circuit is connected with the secondary coil and generates a second rectified voltage from a third AC voltage present at the secondary coil. The second rectified voltage is coupled to a node of the switched-mode power supply and represents or correlates to an output voltage thereof. A monitoring circuit shuts off the inverter when the second rectified voltage or the output voltage exceeds a predetermined first threshold, indicating an idle condition in the load and increasing energy efficiency.