NXP Semiconductors K22F series, Reference Manual, Page: 172 / 1407

LVD system holds the MCU in reset until the supply voltage has risen above the low
voltage detection threshold. The RCM's SRS0[LVD] bit is set following either an LVD
reset or POR.
6.2.2.3 Computer operating properly (COP) watchdog timer
The computer operating properly (COP) watchdog timer (WDOG) monitors the operation
of the system by expecting periodic communication from the software. This
communication is generally known as servicing (or refreshing) the COP watchdog. If this
periodic refreshing does not occur, the watchdog issues a system reset. The COP reset
causes the RCM's SRS0[WDOG] bit to set.
6.2.2.4 Low leakage wakeup (LLWU)
The LLWU module provides the means for a number of external pins, the RESET pin,
and a number of internal peripherals to wake the MCU from low leakage power modes.
The LLWU module is functional only in low leakage power modes.
• In LLS mode, only the RESET pin via the LLWU can generate a system reset.
• In VLLSx modes, all enabled inputs to the LLWU can generate a system reset.
After a system reset, the LLWU retains the flags indicating the input source of the last
wakeup until the user clears them.
NOTE
Some flags are cleared in the LLWU and some flags are
required to be cleared in the peripheral module. Refer to the
individual peripheral chapters for more information.
6.2.2.5 Multipurpose clock generator loss-of-clock (LOC)
The MCG module supports an external reference clock.
If the C6[CME] bit in the MCG module is set, the clock monitor is enabled. If the
external reference falls below f
loc_low
or f
loc_high
, as controlled by the C2[RANGE] field
in the MCG module, the MCU resets. The RCM's SRS0[LOC] bit is set to indicate this
reset source.
Reset
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
172 NXP Semiconductors