ZHCSH93 December   2017 TCAN4420

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      功能框图
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 ESD Ratings Specifications
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Power Supply Characteristics
    7. 6.7 AC and DC Electrical Characteristics
    8. 6.8 Timing Requirements
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 TXD Dominant Time Out (DTO)
      2. 8.3.2 CAN Bus Short Circuit Current Limiting
      3. 8.3.3 Thermal Shutdown
      4. 8.3.4 Under Voltage Lockout (UVLO) and Unpowered Device
        1. 8.3.4.1 VIO Supply PIN
    4. 8.4 Device Functional Modes
      1. 8.4.1 Polarity Configuration
      2. 8.4.2 Normal Polarity Mode
      3. 8.4.3 Reverse Polarity Mode
      4. 8.4.4 Driver and Receiver Function
      5. 8.4.5 Floating Terminals
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 Bus Loading, Length and Number of Nodes
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 CAN Termination
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12器件和文档支持
    1. 12.1 器件支持
      1. 12.1.1 器件命名规则
    2. 12.2 接收文档更新通知
    3. 12.3 社区资源
    4. 12.4 商标
    5. 12.5 静电放电警告
    6. 12.6 Glossary
  13. 13机械、封装和可订购信息

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • D|8
散热焊盘机械数据 (封装 | 引脚)
订购信息

8.3.4 Under Voltage Lockout (UVLO) and Unpowered Device

The VCC and VIO supply terminals have under voltage detection circuitry which places the device in a protected mode if an under voltage fault occurs. This protects the bus during an under voltage event on these terminals. If VIO is under voltage the RXD terminal is tri-stated (high impedance) and the device does not pass any signals from the bus. If VCC supply is lost, or has a brown out that triggers the UVLO, the device transitions to a protected mode. See Table 1.

If VIO drops below UVVIO under voltage detection, the transceiver switches off and disengage from the bus until VIO has recovered.

The device is designed to be an "ideal passive" or “no load” to the CAN bus if the device is unpowered. The bus terminals (CANH, CANL) have extremely low leakage currents when the device is unpowered, so they do not load the bus. This is critical if some nodes of the network are unpowered while the rest of the of network remains operational. Logic terminals also have low leakage currents when the device is unpowered, so they do not load other circuits which may remain powered.

Table 1. Under Voltage Lockout Protection

VCC VIO DEVICE STATE BUS RXD
> UVVCC > UVVIO Normal Per TXD Mirrors Bus
< UVVCC > UVVIO Protected High Impedance High (Recessive)
> UVVCC < UVVIO Protected High Impedance High Impedance
< UVVCC < UVVIO Protected High Impedance High Impedance

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NOTE

Once an under voltage condition is cleared and the VCC supply has returned to valid level the device typically needs tMODE to transition to normal operation. The host processor should not attempt to send or receive messages until this transition time has expired.