ZMOTION AC Load Power Controller Reference Design

This reference design demonstrates how to use Zilog’s ZMOTION MCU with an IR-based motion detector to control power to an AC load in applications such as lighting and HVAC systems. This reference design uses the 8-pin Z8FS040 ZMOTION MCU to intelligently control a mechanical relay and provides adjustable controls for motion sensitivity, delay time and ambient light level.

This new reference design also features Smart Delay technology. With Smart Delay, when motion is detected while the mechanical relay is powered off, the relay’s running time is initially set to a maximum of 10 seconds rather than the full delay time set by the Time Delay potentiometer. If additional motion is detected within this 10-second period, the full delay timer set by the potentiometer is used. If additional motion is not detected, then the 10-second delay expires and the load is switched off.

This methodology is useful for room occupancy detection and lighting control applications. For example, when the delay time is set for durations greater than 10 seconds and a person enters and leaves a room quickly, the lights are not turned on for the duration of the full delay time; instead, they are turned on for only 10 seconds. When an additional Delayed Detection feature is enabled and motion is detected while the delay time is set to 5 minutes or greater, motion is ignored until the final full minute of the delay cycle. This methodology is useful when the delay is set to a long value and the environment is harsh. It serves to ensure that the light does not remain on due to false motion events. When this feature is not enabled and motion is detected, the system immediately starts looking for motion again, and retriggers the output if motion is detected.

“This AC Load Power Controller can be used to develop a number of applications, including remote-operated commercial or architectural lighting, private lighting with remote control convenience features and remote-operated household or industrial equipment,” remarked Steve Darrough, Zilog’s VP of Marketing.