What is the difference between selecting the WDT OSC or the fsys/4 as the WDT clock source?
Answer If the WDT OSC is chosen as the WDT Clock Source, then should the system erroneously enter the Power Down Mode, the WDT Timer will continue to function, and when it times out, the system will be woken up. If fsys/4 clock is selected as the WDT Clock Source, then should the system erroneously enter the Power Down Mode, the clock will stop running and there will be no way for the WDT to wake up the system. However if using the WDT OSC there is a cost incurred, which is that this oscillator will increase slightly the power consumption of the device. For normal system operation, if the Power Down Mode is used normally, and if the Power Down Mode does not require a Watchdog Timer wake up function, then the WDT clock source can be chosen to be fsys/4.
