Microcontroller Supervisory IC Application Note

While the voltage detector built-in the Ricoh watchdog timer is highly accurate, the watchdog timer itself is also highly accurate.  The accuracy of the watchdog timeout period has been significantly improved to ±33% to aid easier system design.
System design must be considered for the dispersion of the watchdog timeout period when sending the SCK pulse to avoid the watchdog timer sending the error reset signals.

*) Accuracy on the center value ((minimum value + maximum value) / 2)

There is no need to design the system to send the SCK pulse frequently to clear the WDT count since Ricoh's Watchdog Timer's timeout period is highly accurate.