In this application, two 2-input NAND gates are used to create an active-low SR latch as shown in Figure 8-1. The two additional gates can be used for a second SR latch, or the inputs can be grounded and both channels left unused.

The SN74AHC1G00-Q1 is used to drive the tamper indicator LED and provide one bit of data to the system controller. When the tamper switch outputs LOW, the output Q becomes HIGH. This output remains HIGH until the system controller addresses the event and sends a LOW signal to the R input which returns the Q output back to LOW.