SLLU312A July 2019 – May 2022 TCAN4550-Q1
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
Safety-Mechanism # | Pin | Pull-up or Pull-down | COMMENT |
---|---|---|---|
SM-20 | SCLK | Pull up | Weakly biases input |
SM-21 | SDI | Pull up | Weakly biases input |
SM-22 | nCS | Pull up | Weakly biases input so the device is not selected |
SM-23 | nWKRQ | Pull up | Weakly biases output when using internal voltage rail. When using open drain configuration an external pull up is needed. |
SM-24 | RST | Pull down | Weakly biases RST pin towards Normal operation mode |
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.