SCLS381M August   1997  – March 2015 SN74LV74A

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Electrical Characteristics
    5. 6.5  Switching Characteristics: VCC = 2.5 V ± 0.2 V
    6. 6.6  Switching Characteristics: VCC = 3.3 V ± 0.3 V
    7. 6.7  Switching Characteristics: VCC = 5 V ± 0.5 V
    8. 6.8  Timing Requirements: VCC = 2.5 V ± 0.2 V
    9. 6.9  Timing Requirements: VCC = 3.3 V ± 0.3 V
    10. 6.10 Timing Requirements: VCC = 5 V ± 0.5 V
    11. 6.11 Noise Characteristics
    12. 6.12 Operating Characteristics
    13. 6.13 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • D|14
  • RGY|14
  • DGV|14
  • PW|14
  • DB|14
  • NS|14
散热焊盘机械数据 (封装 | 引脚)
订购信息

8 Detailed Description

8.1 Overview

These dual positive-edge-triggered D-type flip-flops are designed for 2-V to 5.5-V VCC operation.

A low level at the preset (PRE) or clear (CLR) inputs sets or resets the outputs, regardless of the levels of the other inputs. When PRE and CLR are inactive (high), data at the data (D) inputs meeting the setup-time requirements is transferred to the outputs on the positive-going edge of the clock pulse. Clock triggering occurs at a voltage level and is not directly related to the rise time of the clock pulse. Following the hold-time interval, data at the D input can be changed without affecting the levels at the outputs. The state of the output upon power-up is not known until the first valid clock edge has occurred while VCC is within Recommended Operating Conditions.

These devices are fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the devices when they are powered down.

8.2 Functional Block Diagram

SN54LV74A SN74LV74A logic_cls381.gifFigure 4. Logic Diagram, Each Flip-Flop (Positive Logic)

8.3 Feature Description

The device’s wide operating range allows it to be used in a variety of systems that use different logic levels. The low propagation delay allows fast switching and higher speeds of operation. In addition, the low ground bounce stabilizes the performance of non-switching outputs while another output is switching.

8.4 Device Functional Modes

Table 1. Function Table

INPUTS OUTPUTS
PRE CLR CLK D Q Q
L H X X H L
H L X X L H
L L X X H(1) H(1)
H H ↑ H H L
H H ↑ L L H
H H L X Q0 Q0
(1) This configuration is nonstable; that is, it does not persist when PRE or CLR returns to its inactive (high) level.