Power Supply Scheme - ST STM32H7 3 Series Application Note

AN4938
1.2

Power supply scheme

Power supplies
•
V
DD
blocks such as reset and PLL
This power supply is provided externally through VDD pins. VDD pins must be
connected to V
capacitor (of 4.7 µF minimum capacitance) for the package and a 100 nF ceramic
capacitor for each VDD pin.
When V
Note: V minimum value of 1.62 V is obtained when the internal reset controller is OFF (refer to
DD
Section 1.3.6: Internal reset
•
V
SSA
OPAMPs.
VDDA pin must be connected to two external decoupling capacitors (100 nF ceramic
capacitors and a 1 µF tantalum or ceramic capacitor).
•
V
DD33USB
When VDD50USB is used to provide power, this pin must be connected to the USB
connector VBUS line and to a 4.7 µF decoupling capacitor (C
VDD33USB must be connected to a 1 µF capacitor and its maximum ESR should be
600 mΩ.
When VDD33USB is used to power the USB transceiver (3.0 to 3.6 V), if the
VDD50USB pin is available, it must connected to VDD33USB, which must be
connected to two external decoupling capacitors (a 100 nF ceramic capacitor and a
1 µF tantalum or ceramic capacitor).
•
V
BAT
backup registers (through power switch) when V
The V
external battery is used, it is mandatory to connect this pin to an external power supply:
as an example, V
decoupling capacitor.
•
V
REF+
V
REF+
reference voltage is applied to V
connected on this pin. In all cases, V
is 2 V when V
•
V
DDLDO
When the LDO voltage regulator is enabled, VCAP1 and VCAP2 pins must be
connected to two 2.2 µF ceramic capacitors with a low ESR (< 100 mΩ). If VCAP3 is
available, it must be connected to the other VCAP pins but not additional capacitor is
required. In addition, the VDDLDOx pins must be connected together and to a 4.7 µF
tantalum or ceramic capacitor.
Additional precautions can be taken to filter analog noise:
•
VDDA can be connected to V
•
The VREF+ pin can be connected to V
= 1.62 to 3.6 V: external power supply for I/Os, Flash memory and system analog
with external decoupling capacitors: one single tantalum or ceramic
DD
is lower than 1.71 V, an external reset controller is required.
DD
OFF).
, V = 1.62 to 3.6 V: external analog power supplies for ADCs, DACs and
DDA
and V : external power supplies for USB transceiver
DD50USB
= 1.2 to 3.6 V: power supply for the RTC, the external 32 kHz oscillator and
pin can be connected to the external battery (1.2 V < V
BAT
pin can be connected to V
BAT
external reference voltage for analog peripherals
pin can be connected to V
is above 2 V and the ADC is used, otherwise it is 1.62 V.
DDA
= 1.62 to 3.6 V: external power supply for voltage regulator
DocID029918 Rev 1
DD
through a 100 nF external ceramic
DD
external power supply. If a separate external
DDA
, a 100 nF and a 1 μF capacitors must be
REF+
must be kept below V
REF+
through a ferrite bead.
DD
through a resistor (typically 47 Ω).
DDA
Power supplies
). In addition,
IN
is not present.
< 3.6 V). If no
BAT
. V
DDA REF+
lower limit
11/48
47