An offline power supply includes a power supply circuit including a primary-side circuit for connecting to a power source, a secondary-side circuit for connecting to a load, and a transformer connecting the primary-side circuit and the secondary-side circuit. A switch operates to selectively connect the primary-side circuit to the power source. A trigger circuit is connected to the secondary-side circuit and has at least one input. The trigger circuit generates an output to selectively operate the switch based on the at least one input.