ZHCSO44C February   2021  – December 2021 TCAN1044A-Q1 , TCAN1044AV-Q1

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  ESD Ratings - IEC Specifications
    4. 7.4  Recommended Operating Conditions
    5. 7.5  Thermal Characteristics
    6. 7.6  Supply Characteristics
    7. 7.7  Dissipation Ratings
    8. 7.8  Electrical Characteristics
    9. 7.9  Switching 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
      1. 9.3.1 Pin Description
        1. 9.3.1.1 TXD
        2. 9.3.1.2 GND
        3. 9.3.1.3 VCC
        4. 9.3.1.4 RXD
        5. 9.3.1.5 VIO
        6. 9.3.1.6 CANH and CANL
        7. 9.3.1.7 STB (Standby)
      2. 9.3.2 CAN Bus States
      3. 9.3.3 TXD Dominant Timeout (DTO)
      4. 9.3.4 CAN Bus short-circuit current limiting
      5. 9.3.5 Thermal Shutdown (TSD)
      6. 9.3.6 Undervoltage Lockout
      7. 9.3.7 Unpowered Device
      8. 9.3.8 Floating pins
    4. 9.4 Device Functional Modes
      1. 9.4.1 Operating Modes
      2. 9.4.2 Normal Mode
      3. 9.4.3 Standby Mode
        1. 9.4.3.1 Remote Wake Request via Wake-Up Pattern (WUP) in Standby Mode
      4. 9.4.4 Driver and Receiver Function
  10. 10Application Information Disclaimer
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
        1. 10.2.1.1 CAN Termination
      2. 10.2.2 Detailed Design Procedures
        1. 10.2.2.1 Bus Loading, Length and Number of Nodes
    3. 10.3 System Examples
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 接收文档更新通知
    2. 13.2 支持资源
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 术语表

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9.3.3 TXD Dominant Timeout (DTO)

During normal mode, the only mode where the CAN driver is active, the TXD DTO circuit prevents the local node from blocking network communication in the event of a hardware or software failure where TXD is held dominant longer than the timeout period tTXD_DTO. The TXD DTO circuit is triggered by a falling edge on TXD. If no rising edge is seen before the timeout period of the circuit, tTXD_DTO, the CAN driver is disabled. This frees the bus for communication between other nodes on the network. The CAN driver is reactivated when a recessive signal is seen on the TXD pin, thus clearing the dominant time out. The receiver remains active and biased to VCC/2 and the RXD output reflects the activity on the CAN bus during the TXD DTO fault.

The minimum dominant TXD time allowed by the TXD DTO circuit limits the minimum possible transmitted data rate of the device. The CAN protocol allows a maximum of eleven successive dominant bits (on TXD) for the worst case, where five successive dominant bits are followed immediately by an error frame. The minimum transmitted data rate may be calculated using Equation 1.

Equation 1. Minimum Data Rate = 11 bits / tTXD_DTO = 11 bits / 1.2 ms = 9.2 kbps
GUID-12447194-8BC7-4D2A-85A3-460512B2BCA8-low.gifFigure 9-4 Example Timing Diagram for TXD Dominant Timeout