SLLSFM2A November 2024 – October 2025 TCAN2855-Q1 , TCAN2857-Q1
PRODUCTION DATA
The TCAN285x-Q1 provides three methods for setting up the watchdog, window, timeout and question and answer. Question and Answer watch dog is covered in Question and Answer Watchdog. Refer to Figure 8-61 for the Timeout watchdog timing diagram. Timeout watchdog has an internal accuracy of ±15%.
When using the window watchdog, understanding the closed and open window aspects is important. The device is set up with a 50%/50% open and closed window, and is based on an internal oscillator with a ±10% accuracy range. To determine when to provide the input trigger, the variance needs to be considered. Using the 64ms nominal total window, tWINDOW, provides a closed and open window that are each 32ms. Taking the ±10% internal oscillator into account means tWINDOW can be between 57.6ms and 70.4ms. The closed, tCLOSED, and open window, tOPEN, are between 28.8ms and 35.2ms. Using tOPEN-MIN of 57.6ms and tCLOSED-MAX of 35.2ms, the available safe trigger window is 22.4ms long. The safe trigger area needs to happen at the 46.4ms ± 11.2ms which is half the tOPEN min + tCLOSED max. The same method is used for the other window values. Figure 8-62 provides the above information graphically. This also describes the response 1 and response 2 windows for the Q&A watchdog.