JAJSR59F March   2008  – August 2023 ISO1176

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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  Power Ratings
    6. 6.6  Insulation Specifications
    7. 6.7  Safety-Related Certifications
    8. 6.8  Safety Limiting Values
    9. 6.9  Electrical Characteristics: Driver
    10. 6.10 Electrical Characteristics: Receiver
    11. 6.11 Supply Current
    12. 6.12 Electrical Characteristics: ISODE-Pin
    13. 6.13 Switching Characteristics: Driver
    14. 6.14 Switching Characteristics: Receiver
    15. 6.15 Insulation Characteristics Curves
    16. 6.16 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Device Functional Modes
  10. 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
        1. 9.2.2.1 Transient Voltages
        2. 9.2.2.2 ISO1176 “Sticky Bit” Issue (Under Certain Conditions)
      3. 9.2.3 Application Curve
  11. 10Power Supply Recommendations
  12. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  13. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 サポート・リソース
    3. 12.3 Trademarks
    4. 12.4 静電気放電に関する注意事項
    5. 12.5 用語集
  14. 13Mechanical, Packaging, and Orderable Information

パッケージ・オプション

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

9.2.2.2 ISO1176 “Sticky Bit” Issue (Under Certain Conditions)

Summary: In applications with sufficient differential noise on the bus, the output of the ISO1176 receiver may “stick” at an incorrect state for up to 30 µs.

Description: The ISO1176 isolated Profibus (RS-485) transceiver is rated for signaling up to 40 Mbps on twisted-pair bus lines. The receiver thresholds comply with RS-485 and Profibus specifications; an input differential voltage VID = VA – VB > 200 mV causes a logic High on the R output, and VID < –200 mV causes a logic Low on the R output. To assure a known receiver output when the bus is shorted or idle, the upper threshold is set below zero, such that VID = 0 mV causes a logic High on the R output. The data sheet specifies a typical upper threshold (VIT+) of –80 mV and a typical lower threshold (VIT-) of –120 mV.

At a signaling rate of 40 Mbps, each valid data bit has a duration of 25 ns. At typical Profibus signaling rates of 12 Mbps or lower, each valid data bit has a duration of 83 ns or more. The ISO1176 correctly sets the R output for each of these valid data bits.

In applications with a high degree of differential noise on the bus lines, it is possible to get short periods when an invalid bus voltage triggers a change in state of the internal receiver circuits. An issue with the digital isolation channel in the ISO1176 may cause the invalid receiver state to “stick” rather than immediately transition back to the correct state. The receiver output will always transition to the correct state, but may stick in the incorrect state for up to 30 µs. This can cause a temporary loss of data.

Figure 9-3 shows two cases which could result in temporary loss of data.

GUID-4B5DB40B-50D0-456F-99D0-EA526FC356C2-low.gifFigure 9-3 "Sticky Bit" Issue Waveforms