A start-up circuit for a power converter includes a charging circuit that uses a DC bus voltage of the power converter to generate a charging current to charge an energy storage device to a selected voltage and an auxiliary power output circuit including a transformer primary side auxiliary winding. A control circuit controls one or more switches of the start-up circuit and one or more switches of the power converter primary side. The charging current provides power to the control circuit until the auxiliary power is established. The control circuit disables the start-up circuit when the auxiliary power output is established. The start-up circuit has very low standby power consumption and compact size, and is particularly suitable for power converter applications such as power adapters for portable electronic devices.