
2.1.7
SMPS step-down converter
The embedded switch mode power supply (SMPS) step-down converter has a higher efficiency than the
embedded LDO regulator.
By using the SMPS, the overall system power consumption is improved for all power modes at the extra cost of
an additional external inductor.
Refer to the
STM32H72x and STM32H73x datasheets
to compare power efficiencies.
See
Figure 2. System supply configuration
for the possible configurations.
The SMPS step-down converter is always enabled after Power-on reset when its power supply is provided on the
VDDSMPS pin. If it is disabled, it remains disabled even after any reset except for Power-on reset.
The regulated output at start-up is 1.36 V.
The three main SMPS configurations are:
•
The SMPS is used but the Vcore supply is provided by the internal LDO regulator.
After start-up the SMPS can be set by software to provide a regulated output of 1.8V or 2.5 V.
•
The SMPS is used but the Vcore supply is provided by an external regulator.
After start-up the SMPS can be set by software to provide a regulated output of 1.8 V or 2.5 V. The external
regulator must ensure the correct voltage scaling for the run and stop modes (VOSx and SVOSx).
•
The SMPS is directly connected to the VCAP pin and provides the regulated supply to the Vcore.
In this configuration, the SMPS will run in one of the following modes:
–
Run mode:
◦
The converter can be dynamically scaled by programming the voltage scaling (VOS0 to VOS3) to
the required performance (see the reference manual
STM32H723/733, STM32H725/735 and
STM32H730 advanced Arm
®
-based 32-bit MCUs
(RM0468)).
–
In Stop mode:
◦
The converter output level is reduced to the state programmed before entering stop mode
(SVOS3 to SVOS5). The register and SRAM content is kept
◦
For SVOS3, a further power reduction can be achieved by setting the converter in low power
mode (for SVOS4 and SVOS5 the low-power mode is always set automatically).
–
In Standby mode:
◦
The converter is powered down. Both the register and SRAM content is lost except for the content
related to the standby circuitry and the backup domain.
AN5419
Introduction
AN5419
-
Rev 2
page 14/50