User Manual
377
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
Watchdog Timer (WDT1)
14.3.2
Normal Operation
The software has to trigger the watchdog by writing to the WDT1_TRIG register. By triggering the watchdog
also the length of the next watchdog period is selected inherently. The next period starts immediately with the
trigger.
After Reset the WDT1 is starting with a long open window. The WDT1 has to be triggered within this long open
window otherwise a reset will be generated at the end of the long open window. If the watchdog is not served
properly consecutively 5 times, the system will enter sleep mode. After an initial successful trigger the WDT1
operates in a window watchdog mode. Configuring of a short open window inside the long open window is not
allowed and will also cause a WDT1 reset.
Figure 73 Windowed
Watchdog
The first half of the watchdog period is the closed window and the second half is the open window. A trigger
of the watchdog has to be done in the open window only. Any trigger in the closed window or failing to trigger
the watchdog within the watchdog period will cause a reset. The reset will be indicated by the bit
PMU_ExtWDT
in the reset status register
Effective open window (safe trigger point)
Due to the variations in the clock source of the WDT1 the effective usable open window, and therefore a safe
trigger point, is shorter than 50% of the watchdog period as shown in
.
Watchdog Period
50% of Watchdog Period
50% of Watchdog Period
closed window
open window