SCAS294O JANUARY   1993  – June 2015 SN54LVC257A , SN74LVC257A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Options
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information: 16-Pin Packages
    5. 7.5  Thermal Information: 20-Pin Package
    6. 7.6  Electrical Characteristics
    7. 7.7  SN54LVC257A Switching Characteristics
    8. 7.8  SN74LVC257A Switching Characteristics
    9. 7.9  Operating Characteristics
    10. 7.10 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Related Links
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9 Detailed Description

9.1 Overview

These quadruple 2-line to 1-line data selectors and multiplexers are designed for 1.65-V to 3.6-V VCC operation.

The SNx4LVC257A devices are designed to multiplex signals from 4-bit data sources to 4-output data lines in bus-organized systems. The 3-state outputs do not load the data lines when the output-enable (OE) input is at a high logic level.

9.2 Functional Block Diagram

SN54LVC257A SN74LVC257A LD_CAS294.gif

9.3 Feature Description

Inputs can be driven from either 3.3-V or 5-V devices. This feature allows the use of these devices as translators in a mixed 3.3-V and 5-V system environment. Device features a maximum tpd of 4.6 ns allowing the device to be used in high-speed applications as well.

To ensure the high-impedance state during power up or power down, OE must be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

9.4 Device Functional Modes

Table 1 lists the functional modes for the SN54LVC257A and SN74LVC257A devices.

Table 1. Function Table

INPUTS OUTPUT
Y
OE A/B A B
H X X X Z
L L L X L
L L H X H
L H X L L
L H X H H