ZHCSNF0B May   2018  – October 2021 ISOW1412 , ISOW1432

PRODMIX  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 说明（续）
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1  Absolute Maximum Ratings
    2. 8.2  Recommended Operating Conditions
    3. 8.3  Thermal Information
    4. 8.4  Power Ratings
    5. 8.5  Insulation Specifications
    6. 8.6  Safety-Related Certifications
    7. 8.7  Safety Limiting Values
    8. 8.8  Electrical Characteristics
    9. 8.9  Supply Current Characteristics at VISOOUT = 3.3 V
    10. 8.10 Supply Current Characteristics at  VISOOUT = 5 V
    11. 8.11 Switching Characteristics at VISOOUT = 3.3 V
    12. 8.12 Switching Characteristics at VISOOUT = 5 V
    13. 8.13 Insulation Characteristics Curves
    14. 8.14 Typical Characteristics
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Power Isolation
    3. 10.3 Signal Isolation
    4. 10.4 RS-485
    5. 10.5 Functional Block Diagram
    6. 10.6 Feature Description
      1. 10.6.1 Power-Up and Power-Down Behavior
      2. 10.6.2 Protection Features
      3. 10.6.3 Failsafe Receiver
      4. 10.6.4 Glitch-Free Power Up and Power Down
    7. 10.7 Device Functional Modes
    8. 10.8 Device I/O Schematics
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Data Rate, Bus Length and Bus Loading
        2. 11.2.2.2 Stub Length
        3. 11.2.2.3 Insulation Lifetime
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Documentation Support
      1. 14.1.1 Related Documentation
    2. 14.2 Receiving Notification of Documentation Updates
    3. 14.3 支持资源
    4. 14.4 Trademarks
    5. 14.5 Electrostatic Discharge Caution
    6. 14.6 术语表
  15. 15Mechanical, Packaging, and Orderable Information

10.6.3 Failsafe Receiver

The differential receiver of the ISOW14x2 devices has failsafe protection from invalid bus states caused by:

  • Open bus conditions such as a broken cable or a disconnected connector
  • Shorted bus conditions such as insulation breakdown of a cable that shorts the twisted-pair
  • Idle bus conditions that occur when no driver on the bus is actively driving.

The differential input of the RS-485 receiver is 0 in any of these conditions for a terminated transmission line. The receiver outputs a failsafe logic-high state on R pin so that the output of the receiver is determinate. The receiver thresholds are offset in the receiver design so that the indeterminate range does not include a 0 V differential. See Receiver functional table for more details.