An isolated switching power converter having a primary-side and secondary-side in signal communication with an input and an output is disclosed. The isolated switching power converter comprises a transformer, primary-side switch, secondary-side switch, primary-side controller, and secondary-side controller. The transformer includes a primary-winding and a secondary-winding in signal communication with the input and output. The primary-side switch is in signal communication with the primary-winding and the secondary-side switch is in signal communication with the secondary-winding. The primary-side controller is on the primary-side and the secondary-side controller is on the secondary-side. The primary-side controller is configured to output a control signal for operating the primary-side switch and the secondary-side controller configured to monitor a voltage across the secondary-side switch, output a control signal for switching the secondary-side switch, and turn-off the secondary-side switch at an off-time of the primary-side switch to transmit a data signal to the primary-side controller.