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

8.3.2 Supply Voltage Rail Monitoring

There are three under voltage events monitored in the TCAN1144-Q1 and TCAN1146-Q1, VSUP, VIO and VCC. The three supply terminals are input sources for the TCAN114x-Q1 and have under voltage detection circuitry which places the device in a protected state if an under voltage fault occurs, UVSUP, UVCC and UVIO. This protects the bus during an under voltage event on these terminals. If VSUP is under voltage the device loses the source needed to keep the internal regulators active. This causes the device to go into a state where communication between the microprocessor and the TCAN114x-Q1 is disabled. The TCAN114x-Q1 is not able to receive information from the bus; and thus, does not pass any signals from the bus, including any Bus Wake via BWRR signals to the microprocessor.

Safety mechanisms SM-5, SM-6 and SM-7 cover this.
Table 8-6 UVSUP, UVCC
VSUP VCC DEVICE STATE BUS RXD
> UVSUP > UVCC Normal Per TXD Mirrors Bus
> UVSUP < UVCC Fail-safe or Sleep High Impedance High (Recessive)
< UVSUP NA Power off High Impedance High Impedance

Table 8-7 Under Voltage Lockout
VSUP VIO VCC DEVICE STATE BUS RXD
> UVSUP > UVIO > UVCC Normal Per TXD Mirrors Bus
> UVSUP > UVIO < UVCC Fail-safe or Sleep High Impedance High (Recessive)
< UVSUP > UVIO NA Power Off High Impedance High (Recessive)
> UVSUP < UVIO > UVCC Fail-safe or UVIO Protected —> Sleep High Impedance High Impedance
> UVSUP < UVIO < UVCC Fail-safe or Sleep High Impedance High Impedance
< UVSUP < UVIO NA Power Off High Impedance High Impedance