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-Q1 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-Q1 ideal for the application because it has Schmitt-trigger inputs that do not have input transition rate requirements.