4.7.4.1.2 NRST_OUT External Reset Control
The RSTC can be configured to assert the external reset line (NRST_OUT). The NRST_OUT pin is driven low for a time programmed by RSTC_MR.ERSTL. This assertion duration lasts 2(ERSTL+1) MD_SLCK cycles. This assertion duration time is in the range of 60 µs to 2 seconds. If ERSTL=0, a two slow clock period duration is generated on the NRST_OUT pin.
This feature allows the NRST_OUT line to be compliant with any external devices connected on the system reset (i.e., when external devices require a longer start-up time than the processor system).