
Rev. 1.00
72 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
5 Power Control Unit (PWRCU)
V
CORE
Power Domain
The main functions that include high speed internal oscillator, HSI, MCU core logic, AHB/APB
peripherals and memories and so on are located in this power domain. Once the V
CORE
is powered
up, the POR will generate a reset sequence on the V
CORE
power domain. Subsequently, to enter the
expected power saving mode, the associated control bits including the LDOOFF, ULDOON and
LDOLCM bits must be configured. Then, once a WFI or WFE instruction is executed, the device
will enter the expected power saving mode which will be discussed in the following section.
High Speed Internal Oscillator
The High Speed Internal Oscillator, HSI, is located in the V
CORE
power domain. When exiting from
the Deep-Sleep mode, the HSI clock can be configured as the system clock for a certain period by
setting the PSRCEN bit to 1. This bit is located in the Global Clock Control Register, GCCR, in the
Clock Control Unit, CKCU. The system clock will not be switched back to the original clock source
used before entering the Deep-Sleep mode until the original clock source.
Operation Modes
Run Mode
In the Run mode, the system operates with full functions and all power domains are active. There
are two ways to reduce the power consumption in this mode. The first is to slow down the system
clock by setting the AHBPRE field in the CKCU AHBCFGR register, and the second is to turn
off the unused peripherals clock by setting the APBCCR0 and APBCCR1 registers or slow down
the peripherals clock by setting the APBPCSR0 and APBPCSR1 registers to meet the application
requirement. Reducing the system clock speed before entering the sleep mode will also help to
minimize power consumption.
Additionally, there are several power saving modes to provide maximum optimization between
device performance and power consumption.
Table 12.
Operation Mode Definitions
Mode Name
Hardware Action
Run
After system reset, CPU fetches instructions to execute.
Sleep
CPU clock will be stopped.
Peripherals, Flash and SRAM clocks can be stopped by setting.
Deep-Sleep1 ~ 2
Stop all clocks in the 1.5 V power domain.
Disable HSI, HSE and PLL.
Turn on the ultra-low power ULDO to reduce the V
CORE
power domain current.
Sleep Mode
By default, only the CPU clock will be stopped in the Sleep mode. Clearing the FMCEN or
SRAMEN bit in the CKCU AHBCCR register to zero will have the effect of stopping the Flash
clock or SRAM clock after the system enters the Sleep mode. If it is not necessary for the CPU to
access the Flash memory and SRAM in the Sleep mode, it is recommended to clear the FMCEN
and SRAMEN bits in the AHBCCR register to minimize power consumption. To enter the Sleep
mode, it is only necessary to execute a WFI or WFE instruction and let the SLEEPDEEP bit to be
0. The system will exit from the Sleep mode via any interrupt or event trigger. The accompanying
table provides more information about the power saving modes.