In this application, one 3-input OR gates is used to combine overheat signals to control a fan as shown in Figure 9-1. The other two gates can be used for another application in the system, or the inputs can be grounded and the channels left unused.

This device is used to directly control the Enable pin of a fan driver. The fan driver requires only one input signal to be HIGH before being enabled, and should be disabled in the event that all signals go LOW. The 4-input OR gate function combines the four individual overheat signals into a single active-high enable signal.