SGDS007D May   1998  – February 2024 SN74AHCT00Q-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 Recommended Operating Conditions
    3. 5.3 Thermal Information
    4. 5.4 Electrical Characteristics
    5. 5.5 Switching Characteristics
    6. 5.6 Noise Characteristics
    7. 5.7 Operating Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Balanced CMOS Push-Pull Outputs
      2. 7.3.2 TTL-Compatible CMOS Inputs
      3. 7.3.3 Clamp Diode Structure
      4. 7.3.4 Wettable Flanks
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Power Considerations
        2. 8.2.1.2 Input Considerations
        3. 8.2.1.3 Output Considerations
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

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 SN74AHCT00Q-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 SN74AHCT00Q-Q1 ideal for the application because it has Schmitt-trigger inputs that do not have input transition rate requirements.