In this application, three 2-input AND gates are combined to produce a 4-input AND gate function as shown in Figure 9-1. The fourth gate can be used for another application in the system, or the inputs can be grounded and the channel left unused.

The SN74HCS08 is used to directly control the RESET pin of a motor controller. The controller requires four input signals to all be HIGH before being enabled, and should be disabled in the event that any one signal goes LOW. The 4-input AND gate function combines the four individual reset signals into a single active-low reset signal.

Many power good signals utilize open-drain outputs which can produce slow input transition rates when they transition from LOW to Hi-Z mode. This makes the SN74HCS08 ideal for the application because it has Schmitt-trigger inputs that do not have input transition rate requirements.