8 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

8.1 Application Information

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 SN74AC00-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.

The inputs of this active-low SR latch can often be driven by open-drain outputs which can produce slow input

transition rates when they transition from LOW to Hi-Z. This makes the SN74AC00-Q1 ideal for the application

because it has Schmitt-trigger inputs that do not have input transition rate requirements.

8.2 Typical Application

System

Controller

Tamper

Switch

R

S

Q

R1

Tamper

Indicator

R2

Figure 8-1. Typical Application Block Diagram

www.ti.com

SN74AC00-Q1

SCASE92A – MARCH 2025 – REVISED MARCH 2025

Copyright © 2025 Texas Instruments Incorporated

Submit Document Feedback

13