The TLIN1431x-Q1 provides two methods for setting up the watchdog when in SPI communication mode: window watchdog or timeout watchdog. If more frequent (i.e. <16 ms) input trigger events are desired it is suggested to use the timeout watchdog. When using timeout watchdog, the input trigger can occur anywhere before the timeout and is not tied to an open window.

When using the window watchdog, it is important to understand the closed and open window aspects. 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, this variance needs to be considered. For example, using the 64 ms nominal total window provides a closed and open window that are each 32 ms. Taking the ±10% internal oscillator into account means the total window could range from 57.6 ms to 70.4 ms. The closed and open window could then range from 22.4 ms to 35.2 ms. From the 57.6 ms total window and 35.2 ms closed window, the total open window is 22.4 ms. The trigger event needs to happen at 46.4 ms ± 11.2 ms. The same method is used for the other window values. Figure 7-8 provides the above information graphically.