JAJSV61A March   2003  – August 2024 CD54AC32 , CD74AC32

PRODUCTION DATA  

  1.   1
  2. 特長
  3. 概要
  4. Pin Configuration and Functions
  5. Specifications
    1. 4.1 Absolute Maximum Ratings
    2. 4.2 ESD Ratings
    3. 4.3 Recommended Operating Conditions
    4. 4.4 Thermal Information
    5. 4.5 Electrical Characteristics
    6. 4.6 Switching Characteristics, VCC = 1.5V
    7. 4.7 Switching Characteristics, VCC = 3.3V ± 0.3V
    8. 4.8 Switching Characteristics, VCC = 5V ± 0.5V
    9. 4.9 Operating Characteristics
  6. Parameter Measurement Information
  7. Detailed Description
    1. 6.1 Functional Block Diagram
    2. 6.2 Device Functional Modes
  8. Application and Implementation
    1. 7.1 Power Supply Recommendations
    2. 7.2 Layout
      1. 7.2.1 Layout Guidelines
      2. 7.2.2 Layout Example
  9. Device and Documentation Support
    1. 8.1 Documentation Support (Analog)
      1. 8.1.1 Related Documentation
    2. 8.2 ドキュメントの更新通知を受け取る方法
    3. 8.3 サポート・リソース
    4. 8.4 Trademarks
    5. 8.5 静電気放電に関する注意事項
    6. 8.6 用語集
  10. Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Layout Guidelines

When using multiple bit logic devices inputs should not ever float.

In many cases, functions or parts of functions of digital logic devices are unused, for example, when only two inputs of a triple-input AND gate are used or only 3 of the 4 buffer gates are used. Such input pins should not be left unconnected because the undefined voltages at the outside connections result in undefined operational states. Specified in Layout Example for the CD74AC32 are the rules that must be observed under all circumstances. All unused inputs of digital logic devices must be connected to a high or low bias to prevent them from floating. The logic level that must be applied to any particular unused input depends on the function of the device. Generally they will be tied to GND or VCC; whichever makes more sense or is more convenient. It is generally acceptable to float outputs unless the part is a transceiver. If the transceiver has an output enable pin, it will disable the outputs section of the part when asserted. This will not disable the input section of the IOs, so they cannot float when disabled.