Consistent with example embodiments disclosed, there are switched-mode power supplies (SMPS) in which a signaling capacitor transmits information across a transformer of the power supply. Such embodiments can avoid drawing power from the output capacitor in order to provide communication signals and so do not cause a drop in the output voltage when signaling to the primary side. Further, the switched mode power supply can send signals from the secondary side of the transformer to the primary side via the transformer itself and so may not require the incorporation of an opto-coupler. Such embodiments may reduce production costs, the printed circuit board (PCB) footprint and reduce the no-load power consumption of the SMPS.