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Rev. 1.00
73 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
5 Power Control Unit (PWRCU)
5 Power Control Unit (PWRCU)
Table 13. Enter/Exit Power Saving Modes
Mode
Mode Entry
Mode Exit
CPU
Instruction
CPU
SLEEPDEEP LDOOFF ULDOON
Sleep
WFI or WFE
(Takes effect)
0
X
X
WFI: Any interrupt
WFE:
Any wakeup event
(1)
or
Any interrupt (NVIC on) or
Any interrupt with SEVONPEND = 1
(NVIC off)
Deep-Sleep1
1
0
0
Any EXTI in event mode or
RTC wakeup or
CMP wakeup
(3)
or
LVD wakeup
(2)
or
WAKEUPn pin wakeup
Deep-Sleep2
1
X
1
Any EXTI in event mode or
RTC wakeup or
CMP
(3)
wakeup or
LVD wakeup
(2)
or
WAKEUPn pin wakeup
Notes:
1. Wakeup event means EXTI line trigger event, RTC event, LVD event or WAKEUPn pin wakeup.
2. If the system allows the LVD activity to wake it up after the system has entered the power saving mode,
the LVDEWEN and LVDEN bits in the LVDCSR register must be set to 1 to make sure that the system
can be woken up by an LVD event and then the main LDO can be turned on when the system is woken
up from the Deep-Sleep2 mode.
3. CMP wakeup is only available for the HT32F54243/HT32F54253 devices.
Deep-Sleep Mode
To enter the Deep-Sleep mode, configure the registers as shown in the preceding table and execute
the WFI or WFE instruction. In the Deep-Sleep mode, all clocks including the PLL and high speed
oscillators, known as HSI and HSE, will be stopped. In addition, the Deep-Sleep1 and Deep-
Sleep2 mode will turns off the main LDO and uses an ultra-low power LDO, ULDO, to keep the
V
CORE
power. Once the PWRCU receives a wakeup event or an interrupt as shown in the preceding
Mode-Exiting table, the main LDO will then operate in normal mode and the high speed oscillators
will be enabled. Finally, the CPU will return to the Run mode to handle the wakeup interrupt if
required. A Low Voltage Detection also can be regarded as a wakeup event if the corresponding
wakeup control bit LVDEWEN in the LVDCSR register is enabled. The last wakeup event is a
transition from low to high on the external WAKEUPn pin sent to the PWRCU to resume from the
Deep-Sleep mode. During the Deep-Sleep mode, retaining the register and memory contents will
shorten the wakeup latency.
Table 14. Power Status after System Reset
PORF
PORSTF
Description
1
1
Power-up for the first time after the V
DD
domain is reset:
Power-on reset when V
DD
is applied for the first time or executing software
reset command on the V
DD
domain.
0
1
Restart from unexpected loss of the V
CORE
power or other reset (nRST,
WDT, …)