A controller (606) for a switched mode power supply (100), comprising: a first terminal (620) for receiving a controller input voltage (Vcc); a second terminal for coupling to ground (654); a selectably engagable load (656); a load selector (658) configured to: engage the selectably engagable load between the first and second terminals in order to draw a selectably engagable load current (lextra), and disengage the selectably engagable load from the first and second terminals in accordance with a comparison between a disengagement threshold and the controller input voltage or an input current at the first terminal.