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RM0090
Power controller (PWR)
149
Entering Stop mode (for STM32F405xx/07xx and STM32F415xx/17xx)
The Stop mode is entered according to
Section : Entering low-power mode
, when the
SLEEPDEEP bit in the Cortex
®
-M4 with FPU System Control register is set.
for details on how to enter the Stop mode.
To further reduce power consumption in Stop mode, the internal voltage regulator can be put
in low-power mode. This is configured by the LPDS
bit
of the
(PWR_CR) for STM32F405xx/07xx and STM32F415xx/17xx
register (PWR_CR) for STM32F42xxx and STM32F43xxx
If Flash memory programming is ongoing, the Stop mode entry is delayed until the memory
access is finished.
If an access to the APB domain is ongoing, The Stop mode entry is delayed until the APB
access is finished.
In Stop mode, the following features can be selected by programming individual control bits:
•
Independent watchdog (IWDG): the IWDG is started by writing to its Key register or by
hardware option. Once started it cannot be stopped except by a Reset. See
Section 21: Independent watchdog (IWDG)
.
•
Real-time clock (RTC): this is configured by the RTCEN bit in the
Backup domain control register (RCC_BDCR)
•
Internal RC oscillator (LSI RC): this is configured by the LSION bit in the
Section 7.3.22: RCC clock control & status register (RCC_CSR)
•
External 32.768 kHz oscillator (LSE OSC): this is configured by the LSEON bit in the
Section 7.3.21: RCC Backup domain control register (RCC_BDCR)
The ADC or DAC can also consume power during the Stop mode, unless they are disabled
before entering it. To disable them, the ADON bit in the ADC_CR2 register and the ENx bit
in the DAC_CR register must both be written to 0.
Table 26. Stop operating modes
(STM32F405xx/07xx and STM32F415xx/17xx)
Stop mode
LPDS bit
FPDS bit
Wake-up latency
STOP MR
(Main regulator)
0
0
HSI RC startup time
STOP MR-FPD
0
1
HSI RC startup time +
Flash wakeup time from Power Down
mode
STOP LP
1
0
HSI RC startup time +
regulator wakeup time from LP mode
STOP LP-FPD
1
1
HSI RC startup time +
Flash wakeup time from Power Down
mode +
regulator wakeup time from LP mode