SLLU312A July   2019  – May 2022 TCAN4550-Q1

 

  1.   TCAN4550-Q1 Functional Safety-Manual
  2.   Trademarks
  3. 1Introduction
  4. 2Product Functional Safety-Capability
  5. 3Product Overview
    1. 3.1 Block Diagram
    2. 3.2 Target Applications
      1. 3.2.1 Diagnostic Features
        1. 3.2.1.1 Mode Overview
        2. 3.2.1.2 Sleep Wake Error Timer (SWE)
        3. 3.2.1.3 Undervoltage
        4. 3.2.1.4 Thermal Shut Down
        5. 3.2.1.5 CAN Bus Communication
          1. 3.2.1.5.1 M_CAN
        6. 3.2.1.6 Processor Communication
          1. 3.2.1.6.1 SPI Integrity
            1. 3.2.1.6.1.1 SPI Scratchpad
            2. 3.2.1.6.1.2 SPIERR
            3. 3.2.1.6.1.3 M_CAN Forced Dominant and Recessive
            4. 3.2.1.6.1.4 SPI and FIFO
            5. 3.2.1.6.1.5 ECC for Memory
          2. 3.2.1.6.2 Timeout Watchdog
          3. 3.2.1.6.3 Floating Pins
          4. 3.2.1.6.4 RST Pin
          5. 3.2.1.6.5 Interrupt and Internal Fault Detection
  6. 4Development Process for Management of Systematic Faults
    1. 4.1 TI New-Product Development Process
  7. 5Revision History
3.2.1.6.3 Floating Pins

In case of open (floating pins) default state of pin are provided by integrated pull-up or pull-down resistors incase of an open pin. See Table 3-8 for details on pin bias conditions. These known states help keep device pins at a defined level thus helping mitigate faults 4 and 7

Table 3-8 Terminal Bias
Safety-Mechanism #PinPull-up or Pull-downCOMMENT
SM-20SCLKPull upWeakly biases input
SM-21SDIPull upWeakly biases input
SM-22nCSPull upWeakly biases input so the device is not selected
SM-23nWKRQPull upWeakly biases output when using internal voltage rail. When using open drain configuration an external pull up is needed.
SM-24RSTPull downWeakly biases RST pin towards Normal operation mode
Note:

The internal bias should not be relied upon as only termination, especially in noisy environments but should be considered a fail-safe protection. Special care needs to be taken when the device is used with MCUs using open drain outputs.