ST STM32H743 Series User Manual

DocID029918 Rev 1 7/48
AN4938 Power supplies
47
1 Power supplies
1.1 Introduction
STM32H743/753xx devices require a 1.71 to 3.6 V operating voltage supply (V
DD
), which
can be reduced down to 1.62
V by using an external power supervisor and connecting
PDR_ON pin to V
SS
(refer to the datasheets for details).
The digital power can be supplied either by a internal linear voltage regulator or directly by
an external supply voltage. This digital power voltage can be set dynamically at different
values ranging from 0.7 to 1.2
V, the highest value allowing to achieve the maximum
performance.
The real-time clock (RTC), the RTC backup registers, and the backup SRAM (BKP SRAM)
can be powered from the V
BAT
voltage (1.2 to 3.6 V) when the main V
DD
supply is powered
OFF.
1.1.1 Independent analog supply and reference voltage
To improve analog peripheral performance, the analog peripherals feature an independent
power supply which can be separately filtered and shielded from noise on the PCB:
• The analog supply voltage input is available on a separate VDDA pin.
• An isolated supply ground connection is provided on the pin V
SSA
.
To ensure a better accuracy of low-voltage inputs, the user can connect a separate external
reference voltage on V
REF+
. The voltage applied to V
REF+
ranges from 1.8 V to V
DDA
.
When available (depending on the package), V
REF–
pin must be externally tied to V
SSA
.
V
DDA
minimum value (V
DDA_MIN
) depends on the analog peripheral and on whether a
reference voltage is provided or not:
• If no analog peripheral is used, V
DDAmin
equals 0 V.
• When an ADC or a comparator is used, V
DDA_MIN
equals 1.62 V.
• When a DAC is used, V
DDA_MIN
equals 1.8V.
• When an OPAMP is used, V
DDA_MIN
equals 2.0 V.
• When a reference voltage (VREFBUF_OUT) is provided by the device on V
REF+
pin,
V
DDA_MIN
depends on the required level for this voltage.
1.1.2 USB transceiver independent power supply
There are different ways to supply the USB transceivers, depending on V
DD33USB
and
V
DD50USB
availability:
• When the VDD50USB pin is available, this pin can be used to supply an internal
regulator dedicated to USB transceivers. In this case, VDD50USB pin should receive a
voltage ranging from 4.0 to 5.5
V, typically supplied from the VBUS line of the USB
connector. The regulated power (3.0 to 3.6
V) is available on VDD33USB.
In this configuration V
DD50USB
voltage can rise indifferently after or before V
DD
power
supply (see Figure 3).
An external capacitor must be connected to VDD33USB.

ST STM32H743 Series Specifications

General

Brand	ST
Model	STM32H743 Series
Category	Microcontrollers
Language	English