Driver circuit able to monitor usage of a surge protection arrangement

A driver circuit comprising:

• a mains input;
• a switch mode power converter for delivering an output derived from the mains input by switching using a pulse width modulation signal, wherein the switch mode power converter comprises a pulse width controller for controlling the pulse width and/or duty cycle of the pulse width modulation signal;
• and
• a monitor for monitoring the pulse width and/or duty cycle of the pulse width modulation signal and for detecting a surge event from the pulse width and/or duty cycle, wherein the monitor is for detecting the surge event from changes in the pulse width and/or duty cycle over time, and comprises a monitor circuit for detecting a surge event based on:
• a second pulse width changing to a first pulse width, remaining at the first pulse width for a time period falling within a first threshold range and then returning to the second pulse width, wherein the first pulse width is narrower than the second pulse width;
• or
• a second duty cycle changing to a first duty cycle, remaining at the first duty cycle for a time period falling within a first threshold range and then returning to the second duty cycle, wherein the first duty cycle is smaller than the second duty cycle.