Power converter and method of operating a power converter

A method of operating a power converter comprising:

• transmitting a control signal based on a controlled variable related to an output signal of the power converter from a secondary side of the power converter to a primary side of the power converter via a transformer separating the primary side from the secondary side, wherein the transformer is also used to transfer energy from the primary side to the secondary side;
• starting or stopping an oscillation of a resonant oscillator of the power converter including an inductance provided by the transformer based on the control signal received at the primary side;
• changing a first signal of the control signal from a first state to a second state in response to a controlled variable exceeding a first threshold value, wherein starting or stopping the oscillation comprises stopping the oscillation of the resonant oscillator based on detecting a change of the control signal from the first state to the second state;
• and
• transmitting, as a second signal of the control signal, a wake-up pulse via the transformer to start oscillation of the resonant oscillator in response to the controlled variable falling below a third threshold value.

A power converter, comprising:

• a transformer comprising a primary side winding and a secondary side winding;
• an oscillator circuit coupled to the primary side winding and forming a resonant oscillator with an inductance provided by the transformer;
• an output circuit coupled to the secondary side winding and configured to generate an output signal based on energy received from the secondary side winding;
• a primary side controller;
• and
• a secondary side controller,
• wherein the secondary side controller is configured to transmit a first control signal, via the transformer to the primary side controller, based on a controlled variable related to the output signal, wherein the secondary side controller is configured to change the first control signal from a first state to a second state in response to the controlled variable exceeding a first threshold value,
• wherein the secondary side controller includes a pulse generator configured to generate, as a second control signal, a wake-up pulse in response to the controlled variable falling below a second threshold value, and transmit the wake-up pulse via the transformer to the primary side controller,
• wherein the primary side controller is configured to start or stop an oscillation of the resonant oscillator based on the first control signal, including stopping the oscillation of the resonant oscillator based on detecting the change of the first control signal from the first state to the second state, and
• wherein the primary side controller is configured to start the oscillation of the resonant oscillator based on detecting the wake-up pulse.