STM32U073RCU3 datasheet(12/146 Pages) STMICROELECTRONICS

12 / 146 page

3.7

Low-power modes

By default, the microcontroller is in Run mode after system or power reset. It is up to the user to select one of the

low-power modes described below:

•

Sleep mode

In Sleep mode, only the CPU is stopped. All peripherals continue to operate and can wake up the CPU

when an interrupt/event occurs.

•

Low-power run mode

This mode is achieved with VCORE supplied by the low-power regulator to minimize the regulator operating

current. The code can be executed from SRAM or from flash, and the CPU frequency is limited to 2 MHz.

The peripherals with independent clock can be clocked by HSI16.

•

Low-power sleep mode

This mode is entered from the low-power run mode. Only the CPU clock is stopped. When the wake-up is

triggered by an event or an interrupt, the system reverts to the Low-power run mode.

•

Stop 0, Stop 1, and Stop 2 modes

The Stop modes achieve a lowest power consumption while retaining the content of SRAM and registers.

All the clocks in the VCORE domain are stopped, the PLL, the MSI RC, the HSI16 RC and the HSE crystal

oscillators are disabled. The LSE and LSI clocks are still running.

The RTC can remain active (Stop mode with RTC, Stop mode without RTC).

Some peripherals with the wake-up capability can enable the HSI16 RC during Stop mode, to detect their

wake-up condition.

Three Stop modes are available, Stop 0, Stop 1 and Stop2:

–

In Stop2 mode, most of the VCORE domain is put in lower-leakage mode.

–

Stop 1 offers the largest number of active peripherals and wake-up sources, a smaller wake-up time,

but with a higher consumption than Stop 2 mode.

–

In Stop 0 mode, the main regulator remains on, allowing a very fast wake-up time, but with a much

higher consumption.

When exiting from Stop 0, Stop 1 or Stop 2 mode, the system clock can be either the MSI clock (up to

48 MHz) or HSI16, depending on software configuration.

•

Standby mode

The Standby mode is used to achieve one of the lowest power consumption, with POR/PDR always active

in this mode. The main regulator is switched off to power down VCORE domain. The low-power regulator is

either switched off or kept active. In the latter case, it only supplies SRAM to ensure data retention. The

PLL, as well as the HSI16 RC oscillator and the HSE crystal oscillator are also powered down. The RTC

can remain active (Standby mode with RTC, Standby mode without RTC).

For each I/O, the software can determine whether a pull-up, a pull-down or no resistor must be applied to

that I/O during Standby mode.

Upon entering Standby mode, register contents are lost except for registers in the RTC domain and

standby circuitry. The SRAM contents can be retained through register setting.

The device exits Standby mode upon external reset event (NRST pin), IWDG reset event, wake-up event

(WKUP pin, configurable rising or falling edge) or RTC event (alarm, periodic wake-up, timestamp, tamper),

or when a failure is detected on LSE (CSS on LSE).

•

Shutdown mode

The Shutdown mode enables 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 wake-up, timestamp, tamper).

The system clock after wake-up is MSI at 4 MHz.

STM32U073x8/B/C

Functional overview

DS14548 - Rev 2

page 12/146

STM32U073RCU3 Datasheet(PDF) 12 Page - STMicroelectronics

STM32U073RCU3 Datasheet(HTML) 12 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL