NXP Semiconductors K32 L2A Series, Reference Manual, Page: 1128 / 1379

44.4.5.2 Very-Low-Power Stop (VLPS) mode
The two ways in which VLPS mode can be entered are listed here.
• Entry into stop via the sleep-now or sleep-on-exit with the SLEEPDEEP bit set in the
System Control Register in the Arm core while the MCU is in VLPR mode and
PMCTRL[STOPM] = 010 or 000.
• Entry into stop via the sleep-now or sleep-on-exit with the SLEEPDEEP bit set in the
System Control Register in the Arm core while the MCU is in normal RUN mode
and PMCTRL[STOPM] = 010. When VLPS is entered directly from RUN mode, exit
to VLPR is disabled by hardware and the system will always exit back to RUN.
In VLPS, the on-chip voltage regulator remains in its stop regulation state as in VLPR.
A module capable of providing an asynchronous interrupt to the device takes the device
out of VLPS and returns the device to VLPR mode.
A system reset will also cause a VLPS exit, returning the device to normal RUN mode.
A system reset will cause an exit from VLPS mode, temporarily returning the device to
RUN mode before transitioning into VLPR during the MCU reset flow.
44.4.5.3 Low-Leakage Stop (LLSx) modes
This device contains two Low-Leakage Stop modes: LLS3 and LLS2. LLS or LLSx is
often used in this document to refer to both modes. All LLS modes can be entered from
normal RUN or VLPR modes.
The MCU enters LLS mode if:
• In Sleep-Now or Sleep-On-Exit mode, SLEEPDEEP is set in the System Control
Register in the Arm core, and
• The device is configured as shown in Table 44-2 .
In LLS, the on-chip voltage regulator is in stop regulation. Most of the peripherals are put
in a state-retention mode that does not allow them to operate while in LLS.
Before entering LLS mode, the user should configure the Low-Leakage Wake-up
(LLWU) module to enable the desired wake-up sources. The available wake-up sources
in LLS are detailed in the chip configuration details for this device.
After wakeup from LLS, the device returns to the run mode from which LLS was entered
(either normal RUN or VLPR) with a pending LLWU module interrupt. If LLS was
entered from VLPR mode, then the MCU will begin VLPR entry shortly after wake-up.
In the LLWU interrupt service routine (ISR), the user can poll the LLWU module wake-
up flags to determine the source of the wakeup.
Functional description
K32 L2A Reference Manual, Rev. 2, 01/2020
1128 NXP Semiconductors