Power controller (PWR) RM0090
122/1749 RM0090 Rev 18
scale 3 is automatically selected.(see Section 5.4.1: PWR power control register
(PWR_CR) for STM32F405xx/07xx and STM32F415xx/17xx.
2 operating modes are available:
– Normal mode: The CPU and core logic operate at maximum frequency at a given
voltage scaling (scale 1, scale 2 or scale 3)
– Over-drive mode: This mode allows the CPU and the core logic to operate at a
higher frequency than the normal mode for the voltage scaling scale 1 and scale
2.
• In Stop mode: the main regulator or low-power regulator supplies a low-power voltage
to the 1.2V domain, thus preserving the content of registers and internal SRAM.
The voltage regulator can be put either in main regulator mode (MR) or in low-power
mode (LPR). Both modes can be configured by software as follows:
– Normal mode: the 1.2 V domain is preserved in nominal leakage mode. It is the
default mode when the main regulator (MR) or the low-power regulator (LPR) is
enabled.
– Under-drive mode: the 1.2 V domain is preserved in reduced leakage mode. This
mode is only available with the main regulator or in low-power regulator mode
(see
Table 22).
• In Standby mode: the regulator is powered down. The content of the registers and
SRAM are lost except for the Standby circuitry and the backup domain.
Note: Over-drive and under-drive mode are not available when the regulator is bypassed.
For more details, refer to the voltage regulator section in the STM32F42xxx and
STM32F43xxx datasheets.
Table 22. Voltage regulator configuration mode versus device operating mode
(1)
1. ‘-’ means that the corresponding configuration is not available.
Voltage regulator
configuration
Run mode Sleep mode Stop mode Standby mode
Normal mode MR MR MR or LPR -
Over-drive
mode
(2)
2. The over-drive mode is not available when V
DD
= 1.8 to 2.1 V.
MR MR - -
Under-drive mode - - MR or LPR -
Power-down
mode
---Yes
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