STM32U073RCU6TR datasheet(11/146 Pages) STMICROELECTRONICS

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3.6.3

Voltage regulator

Two embedded linear voltage regulators, main regulator (MR), and low-power regulator (LPR), supply most of

digital circuitry in the device:

•

The MR is used in Run, Sleep and Stop 0 modes.

•

The LPR is used in Low-power run, Low-power sleep, Stop 1, and Stop 2 modes. It is also used to supply

the 8-Kbyte SRAM2 in Standby mode, in order to ensure SRAM2 retention.

Both regulators are powered down in Standby and Shutdown modes: the regulator output is in high impedance,

and the kernel circuitry is powered down, thus inducing zero consumption.

3.6.4

VBAT operation

The VBAT power domain, consuming very little energy, includes RTC, and LSE oscillator and backup registers.

In VBAT mode, the RTC domain is supplied from VBAT pin. The power source can be, for example, an external

battery or an external supercapacitor. Two anti-tamper detection pins are available.

The RTC domain can also be supplied from VDD/VDDA pin.

By means of a built-in switch, an internal voltage supervisor allows automatic switching of RTC domain powering

between VDD and voltage from VBAT pin to ensure that the supply voltage of the RTC domain (VBAT) remains

within valid operating conditions. If both voltages are valid, the RTC domain is supplied from VDD/VDDA pin.

An internal circuit for charging the battery on VBAT pin can be activated if the VDD voltage is within a valid range.

Note:

External interrupts and RTC alarm/events cannot cause the microcontroller to exit the VBAT mode, as in that

mode the VDD is not within a valid range.

STM32U073x8/B/C

Functional overview

DS14548 - Rev 2

page 11/146

STM32U073RCU6TR Datasheet(PDF) 11 Page - STMicroelectronics