A typical application for the Si87xx is a microcontroller controlled actuator in a factory automation system. In the block diagram shown on this slide, the low voltage MCU on the left starts the process, which requires the actuator, and keeps track of the results. The actuator sits on a different PCB and is supplied from a different power system. The Si87xx isolators allow the start signal to pass from the microcontroller, connected to one common, to the actuator board which has a different ground reference. No current can flow between the two separate ground references. The second Si87xx isolator provides the feedback signal back to the control microcontroller.