Power control (PWR) RM0351
142/1693 DocID024597 Rev 3
regulator is in low-power mode to minimize the regulator's operating current. Refer to
Section 5.3.2: Low-power run mode (LP run).
• Low-power sleep mode: This mode is entered from the Low-power run mode: Cortex
®
-
M4 is off. Refer to Section 5.3.5: Low-power sleep mode (LP sleep).
• Stop 0, Stop 1 and Stop 2 modes: SRAM1, SRAM2 and all registers content are
retained. All clocks in the V
CORE
domain are stopped, the PLL, the MSI, the HSI16 and
the HSE are disabled. The LSI and the LSE can be kept running.
The RTC can remain active (Stop mode with RTC, Stop mode without RTC).
Some peripherals with the wakeup capability can enable the HSI16 RC during the Stop
mode to detect their wakeup condition.
In Stop 2 mode, most of the V
CORE
domain is put in a lower leakage mode.
Stop 1 offers the largest number of active peripherals and wakeup sources, a smaller
wakeup time but a higher consumption than Stop 2. In Stop 0 mode, the main regulator
remains ON, which allows the fastest wakeup time but with much higher consumption.
The active peripherals and wakeup sources are the same as in Stop 1 mode.
The system clock, when exiting from Stop 0, Stop 1 or Stop 2 mode, can be either MSI
up to 48 MHz or HSI16, depending on the software configuration.
Refer to Section 5.3.6: Stop 0 mode and Section 5.3.8: Stop 2 mode.
• Standby mode: V
CORE
domain is powered off. However, it is possible to preserve the
SRAM2 contents:
– Standby mode with SRAM2 retention when the bit RRS is set in PWR_CR3
register. In this case, SRAM2 is supplied by the low-power regulator.
– Standby mode when the bit RRS is cleared in PWR_CR3 register. In this case the
main regulator and the low-power regulator are powered off.
All clocks in the V
CORE
domain are stopped, the PLL, the MSI, the HSI16 and the HSE
are disabled. The LSI and the LSE can be kept running.
The RTC can remain active (Standby mode with RTC, Standby mode without RTC).
The system clock, when exiting Standby modes, is MSI from 1 MHz up to 8 MHz.
Refer to Section 5.3.9: Standby mode.
• Shutdown mode: V
CORE
domain is powered off. All clocks in the V
CORE
domain are
stopped, the PLL, the MSI, the HSI16, the LSI and the HSE are disabled. The LSE can
be kept running. The system clock, when exiting the Shutdown mode, is MSI at 4 MHz.
In this mode, the supply voltage monitoring is disabled and the product behavior is not
guaranteed in case of a power voltage drop. Refer to Section 5.3.10: Shutdown mode.
In addition, the power consumption in Run mode can be reduced by one of the following
means:
• Slowing down the system clocks
• Gating the clocks to the APB and AHB peripherals when they are unused.
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