The present invention provides an apparatus and method for reducing the voltage stress in a single-stage single-switch (SSSS) converter by modulating the predetermined operating frequency of the converter lower responsive to increasing voltage stress. A control circuit (116) and associated cooperable frequency setting capacitance (CT) and resistance (RT) are coupled to the primary circuit (112) and the secondary circuit (114) of the SSSS converter via a switch (120). A frequency foldback device (180) is coupled to CT or RT and cooperable therewith to lower bus voltage stress by modulating the switch frequency. The operating frequency is modulated (i.e. reduced) from the predetermined operating frequency upon detection of a voltage threshold transition.