SLLA475 December   2020 TCAN1144-Q1 , TCAN1146-Q1

 

  1. 1TCAN1144-Q1 and TCAN1146-Q1 Functional Safety Manual
  2. 2Trademarks
  3. 3Introduction
  4. 4TCAN114x-Q1 Hardware Component Functional Safety Capability
  5. 5Development Process for Management of Systematic Faults
    1. 5.1 TI New-Product Development Process
  6. 6TCAN1144-Q1 and TCAN1146-Q1 Component Overview
    1. 6.1 Targeted Applications
    2. 6.2 Hardware Component Functional Safety Concept
    3. 6.3 Functional Safety Constraints and Assumptions
  7. 7Description of Hardware Component Parts
    1. 7.1 CAN Transceiver
    2. 7.2 Digital Core
    3. 7.3 EEPROM
    4. 7.4 Power Control IP
      1. 7.4.1 Voltage Monitors
    5. 7.5 Thermal Shut Down
    6. 7.6 Digital Input/Outputs
  8. 8TCAN1144-Q1 and TCAN1146-Q1 Management of Random Faults
    1. 8.1 Fault Reporting
    2. 8.2 Functional Safety Mechanism Categories
    3. 8.3 Description of Functional Safety Mechanisms
      1. 8.3.1 CAN Communication
        1. 8.3.1.1 SM-1: CAN bus fault diagnostic
        2. 8.3.1.2 SM-2: Thermal shutdown; TSD
        3. 8.3.1.3 SM-3: CAN bus short circuit limiter, IOS
        4. 8.3.1.4 SM-4: CAN TXD pin dominant state timeout; tTXD_DTO
        5. 8.3.1.5 SM-17: CAN protocol
      2. 8.3.2 Supply Voltage Rail Monitoring
        1. 8.3.2.1 SM-5: VCC undervoltage; UVCC
        2. 8.3.2.2 SM-6: VSUP supply undervoltage; UVSUP
        3. 8.3.2.3 SM-7: VIO supply undervoltage; UVIO
      3. 8.3.3 SPI/Processor Communication
        1. 8.3.3.1 SM-8: Timout, Window or Q&A watchdog error - Normal mode
        2. 8.3.3.2 SM-9: SPI communication error; SPIERR
        3. 8.3.3.3 SM-10: Scratchpad write/read
        4. 8.3.3.4 SM-11: Sleep Wake Error Timer; tINACTIVE
      4. 8.3.4 Device Internal EEPROM
        1. 8.3.4.1 SM-12: Internal memory CRC; CRC_EEPROM
      5. 8.3.5 Floating Pins
        1. 8.3.5.1 SM-13: SCLK internal pull-up to VIO
        2. 8.3.5.2 SM-14: SDI internal pull-up to VIO
        3. 8.3.5.3 SM-15: nCS internal pull-up to VIO
        4. 8.3.5.4 SM-16: TXD internal pull-up to VIO
          1.        B Revision History

8.3.1.1 SM-1: CAN bus fault diagnostic

The TCAN1144-Q1 and TCAN1146-Q1 provides advanced bus fault detection. TCAN1146-Q1 is used for illustration purposes. The device can determine certain fault conditions and set a status/interrupt flag so that the MCU can understand what the fault is. Detection takes place and is recorded if the fault is present during four dominant to recessive transitions with each dominant bit being > 1.5 μs. As with any bus architecture where termination resistors are at each end not every fault can be specified to the lowest level, meaning exact location. The fault detection circuitry is monitoring the CANH and CANL pins (currents) to determine if there is a short to battery, short to ground, short to each other or opens. From a system perspective, the location of the device also determine what can be detected. See device data sheet for detailed desciption of the CAN bus fault diagnostic.