A secondary side controller for a switched mode power supply, the controller comprising a first semiconductor die comprising an integrated circuit configured to provide a load connection signal; a second semiconductor die, packaged with the first semiconductor die, comprising a charge pump configured to, in response to the load connection signal received from the integrated circuit of the first semiconductor die, provide a switch signal for control of a load connection switch that controls whether or not the switched mode power supply is electrically connected to a load; wherein the presence or absence of the load connection signal is configured to control whether or not the charge pump generates the switch signal and the amplitude of the load connection signal is configured to control the voltage of the switch signal.