Datasheet

Functional overview STM32L431xx
22/200 DocID028800 Rev 1
RC, the HSI16 RC and the HSE crystal oscillators are disabled. The LSE or LSI is still
running.
The RTC can remain active (Stop mode with RTC, Stop mode without RTC).
Some peripherals with wakeup capability can enable the HSI16 RC during Stop mode
to detect their wakeup condition.
Three Stop modes are available: Stop 0, Stop 1 and Stop 2 modes. In Stop 2 mode,
most of the VCORE 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, allowing a very fast wakeup time but with much higher consumption.
The system clock when exiting from Stop 0, Stop1 or Stop2 modes can be either MSI
up to 48 MHz or HSI16, depending on software configuration.
Standby mode
The Standby mode is used to achieve the lowest power consumption with BOR. The
internal regulator is switched off so that the VCORE domain is powered off. The PLL,
the MSI RC, the HSI16 RC and the HSE crystal oscillators are also switched off.
The RTC can remain active (Standby mode with RTC, Standby mode without RTC).
The brown-out reset (BOR) always remains active in Standby mode.
The state of each I/O during standby mode can be selected by software: I/O with
internal pull-up, internal pull-down or floating.
After entering Standby mode, SRAM1 and register contents are lost except for registers
in the Backup domain and Standby circuitry. Optionally, SRAM2 can be retained in
Standby mode, supplied by the low-power Regulator (Standby with RAM2 retention
mode).
The device exits Standby mode when an external reset (NRST pin), an IWDG reset,
WKUP pin event (configurable rising or falling edge), or an RTC event occurs (alarm,
periodic wakeup, timestamp, tamper) or a failure is detected on LSE (CSS on LSE).
The system clock after wakeup is MSI up to 8 MHz.
Shutdown mode
The Shutdown mode allows to achieve the lowest power consumption. The internal
regulator is switched off so that the VCORE domain is powered off. The PLL, the
HSI16, the MSI, the LSI and the HSE oscillators are also switched off.
The RTC can remain active (Shutdown mode with RTC, Shutdown mode without RTC).
The BOR is not available in Shutdown mode. No power voltage monitoring is possible
in this mode, therefore the switch to Backup domain is not supported.
SRAM1, SRAM2 and register contents are lost except for registers in the Backup
domain.
The device exits Shutdown mode when an external reset (NRST pin), a WKUP pin
event (configurable rising or falling edge), or an RTC event occurs (alarm, periodic
wakeup, timestamp, tamper).
The system clock after wakeup is MSI at 4 MHz.
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.