ZHCSN53B December   2019  – March 2021 SN74LXCH8T245

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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  Thermal Information
    5. 6.5  Electrical Characteristics
    6. 6.6  Switching Characteristics, VCCA = 1.2 ± 0.1 V
    7. 6.7  Switching Characteristics, VCCA = 1.5 ± 0.1 V
    8. 6.8  Switching Characteristics, VCCA = 1.8 ± 0.15 V
    9. 6.9  Switching Characteristics, VCCA = 2.5 ± 0.2 V
    10. 6.10 Switching Characteristics, VCCA = 3.3 ± 0.3 V
    11. 6.11 Switching Characteristics, VCCA = 5.0 ± 0.5 V
    12. 6.12 Switching Characteristics: Tsk, TMAX
    13. 6.13 Operating Characteristics
    14. 6.14 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Load Circuit and Voltage Waveforms
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  CMOS Schmitt-Trigger Inputs with Integrated Pulldowns
        1. 8.3.1.1 Control Inputs with Integrated Static Pull-Down Resistors
      2. 8.3.2  Balanced High-Drive CMOS Push-Pull Outputs
      3. 8.3.3  Partial Power Down (Ioff)
      4. 8.3.4  VCC Isolation and VCC Disconnect
      5. 8.3.5  Over-Voltage Tolerant Inputs
      6. 8.3.6  Glitch-Free Power Supply Sequencing
      7. 8.3.7  Negative Clamping Diodes
      8. 8.3.8  Fully Configurable Dual-Rail Design
      9. 8.3.9  Supports High-Speed Translation
      10. 8.3.10 Bus-Hold Data Inputs
    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 Curve
  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 接收文档更新通知
    3. 12.3 支持资源
    4. 12.4 Trademarks
    5. 12.5 静电放电警告
    6. 12.6 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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8.1 Overview

The SN74LXCH8T245 is an 8-bit translating transceiver that uses two individually configurable power-supply rails. The device is operational with VCCA and VCCB supplies as low as 1.1 V and as high as 5.5 V. Additionally, the device operates with VCCA = VCCB. The A port is designed to track VCCA, and the B port is designed to track VCCB.

The SN74LXCH8T245 device is designed for asynchronous communication between data buses and transmits data from the A bus to the B bus or from the B bus to the A bus based on the logic level of the direction-control input (DIR). The output-enable input (OE) is used to disable the outputs so the buses are effectively isolated. The control pins of the SN74LXCH8T245 (DIR and OE) are referenced to VCCA. The OE pin should be tied to VCCA through a pullup resistor to ensure the high-impedance state of the level shifter I/Os during power up or power down.

This device is fully specified for partial-power-down applications using the Ioff current. The Ioff protection circuitry ensures that no excessive current is drawn from or sourced into an input, output, or I/O while the device is powered down.

The VCC isolation and VCC disconnect feature ensures that if either VCC is less than 100 mV or floating with the complementary supply within the recommended operating conditions, both I/O ports are set to the high-impedance state by disabling their outputs and the supply current is maintained.

Glitch-free power supply sequencing allows either supply rail to power on or off in any order while providing robust power sequencing performance.