Datasheet

DocID027107 Rev 6 25/202
STM32F446xC/E Functional overview
40
There are three power modes configured by software when the regulator is ON:
• MR mode used in Run/sleep modes or in Stop modes
– In Run/Sleep mode
The MR mode is used either in the normal mode (default mode) or the over-drive
mode (enabled by software). Different voltages scaling are provided to reach the
best compromise between maximum frequency and dynamic power consumption.
The over-drive mode allows operating at a higher frequency than the normal mode
for a given voltage scaling.
– In Stop modes
The MR can be configured in two ways during stop mode:
MR operates in normal mode (default mode of MR in stop mode)
MR operates in under-drive mode (reduced leakage mode).
• LPR is used in the Stop modes:
The LP regulator mode is configured by software when entering Stop mode.
Like the MR mode, the LPR can be configured in two ways during stop mode:
– LPR operates in normal mode (default mode when LPR is ON)
– LPR operates in under-drive mode (reduced leakage mode).
• Power-down is used in Standby mode.
The Power-down mode is activated only when entering in Standby mode. The regulator
output is in high impedance and the kernel circuitry is powered down, inducing zero
consumption. The contents of the registers and SRAM are lost.
Refer to Table 3 for a summary of voltage regulator modes versus device operating modes.
Two external ceramic capacitors should be connected on V
CAP_1
and V
CAP_2
pin.
All packages have the regulator ON feature.
3.17.2 Regulator OFF
This feature is available only on packages featuring the BYPASS_REG pin. The regulator is
disabled by holding BYPASS_REG high. The regulator OFF mode allows to supply
externally a V
12
voltage source through V
CAP_1
and V
CAP_2
pins.
Table 3. 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
= 1.7 to 2.1 V.
MR MR - -
Under-drive mode - - MR or LPR -
Power-down
mode
---Yes
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