SCLS769B July 2019 – September 2019 SN74HCS32-Q1
In this application, three 2-input OR gates are combined to produce a 4-input OR gate function as shown in Figure 9. The fourth gate can be used for another application in the system, or the inputs can be grounded and the channel left unused.
The SN74HCS32-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 4-input OR gate function combines the four 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 SN74HCS32-Q1 ideal for the application since it has Schmitt-trigger inputs that do not have input transition rate requirements.