9.1 Application Information

The SN74HCS4075-Q1 includes three 3-input OR gates with Schmitt-trigger inputs. These 3-input OR gates work independently, but can be combined to get up to a 7-input OR gate. It can be used with all three inputs active, or one input can be disabled by directly connecting it to ground to turn the device into a 2-input OR gate.

The SN74HCS4075-Q1 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 3-input OR gate function combines the three individual overheat signals into a single active-high enable signal.

Temperature sensors can often be spread throughout a system rather than being in a centralized location. This would mean longer length traces or wires to pass signals through leading to slower edge transitions. This makes the SN74HCS4075-Q1 ideal for the application since it has Schmitt-trigger inputs that do not have input transition rate requirements.