SDLS146B October   1976  – September 2016 SN54LS245 , SN74LS245

 

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  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
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 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
      1. 9.3.1 3-State outputs
      2. 9.3.2 PNP Inputs
      3. 9.3.3 Hysteresis on Bus Inputs
    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 Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Related Links
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Community Resource
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

パッケージ・オプション

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メカニカル・データ（パッケージ｜ピン）
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サーマルパッド・メカニカル・データ
発注情報

9 Detailed Description

9.1 Overview

The SNx4LS245 uses Schottky transistor logic to perform the standard '245 transceiver function. This standard logic function has a common pinout, direction select pin, and active-low output enable. When the outputs are disabled, the A and B sides of the device are effectively isolated.

9.2 Functional Block Diagram

SN54LS245 SN74LS245 logic_dls146.gif Figure 3. Logic Diagram (Positive Logic)

9.3 Feature Description

9.3.1 3-State outputs

The 3-state outputs can drive bus lines directly. All outputs can be put into high impedance mode through the OE pin.

9.3.2 PNP Inputs

This device has PNP inputs which reduce dc loading on bus lines.

9.3.3 Hysteresis on Bus Inputs

The bus inputs have built-in hysteresis that improves noise margins.

9.4 Device Functional Modes

The SNx4LS245 performs the standard '245 logic function. Data can be transmitted from A to B or from B to A depending on the DIR pin value, or the A and B sides can be isolated from one another by setting the OE pin HIGH.

Table 1. Function Table

INPUTS OPERATION
OE DIR
L L B data to A bus
L H A data to B bus
H X Isolation
SN54LS245 SN74LS245 schematic_dls146.gif Figure 4. Schematics of Inputs and Outputs