UCC24650 is an easy-to-use secondary-side voltage monitor from Texas Instruments. The device periodically measures its own VDD voltage. A relative decrease of 3% compared to previous readings triggers an alarm signal to the receiving Primary Side Regulation (PSR) controller. Its low power consumption helps achieve standby losses of less than 5mW in many applications.
An internal 200V MOSFET switch is connected across the ground-referenced rectifier to provide a current-limiting pulse to the flyback transformer secondary winding, which couples the signal to the primary-side controller. This signal is repeated at 33 kHz until a controller-driven switching action is detected.
