Prediction and recovery of zero-crossing information and selective control signal pulse duration

An electrical load controller for controlling conduction of a supply of alternating current (AC) power to a load, the electrical load controller comprising:

• a line input terminal and a load output terminal, the line input terminal configured to be electrically coupled to the supply of AC power, and the load output terminal configured to be electrically coupled to the load;
• a switching circuit electrically coupled in series between the line input terminal and the load output terminal, the switching circuit having an ON state in which the switching circuit conducts the supply of AC power to the load, and an OFF state in which the switching circuit does not conduct the supply of AC power to the load, the switching circuit configured to be selectively controlled by varying a control signal to the switching circuit between the ON state and the OFF state;
• and
• a controller configured to perform:
• selecting a detection window of time having a duration based on a predetermined duration of time, the selected detection window extending from a selected first time to a selected second time and straddling an expected time of a next zero-crossing of an alternating current (AC) waveform the AC waveform oscillating though full cycles, each full cycle comprising a positive half cycle and a negative half cycle;
• monitoring a zero-crossing signal for a zero-crossing indication, of the next zero-crossing, occurring within the selected detection window;
• ascertaining a time of the next zero-crossing based on the monitoring;
• and
• selectively controlling a supply of AC power to a load, wherein the controlling uses the ascertained time of the next zero-crossing of the AC waveform to fire a switching circuit of the electrical load controller.

A method of operating an electrical load controller, the method comprising:

• selecting a detection window of time having a duration based on a predetermined duration of time, the selected detection window extending from a selected first time to a selected second time and straddling an expected time of a next zero-crossing of an alternating current (AC) waveform, the AC waveform oscillating though full cycles, each full cycle comprising a positive half cycle and a negative half cycle;
• monitoring a zero-crossing signal for a zero-crossing indication, of the next zero-crossing, occurring within the selected detection window;
• ascertaining a time of the next zero-crossing based on the monitoring;
• and
• selectively controlling a supply of AC power to a load, wherein the controlling uses the ascertained time of the next zero-crossing of the AC waveform to fire a switching circuit of the electrical load controller.