AN4938 Rev 4 13/46
AN4938 Power supplies
45
Four additional power supplies and pins are used on devices that feature the SMPS:
• V
DDSMPS
= 1.62 to 3.6 V: SMPS step-down converter power supply
V
DDSMPS
must be kept at the same voltage level as V
DD
.
VDDSMPS pin must be connected to an external 4.7 F capacitor with a 100 m
equivalent series resistance (ESR).
VSSSMPS is the SMPS step-down converter ground.
• V
LXSMPS
: SMPS step-down converter supply
VLXSMPS
output is coupled to a 2.2 H inductor with a 220 pF external capacitor.
• V
FBSMPS
= V
CORE
= 1.8 or 2.5 V: external SMPS step-down converter sense feedback
voltage
VFBSMPS input pin must be connected to a 10 F cap
acitor with a 20 m ESR.
Note: Refer to the corresponding datasheet for more details regarding the external components
re
quired for the SMPS.
Four additional power supplies and pins are available
to supply the internal DSI regulator on
STM32H7x7I/G devices:
• V
DDDSI
= 1.8 to 3.6 V: supply voltage for the DSI internal regulator
VDDDSI is the DSI regulator supply
input, while VSSDSI is the DSI regulator ground.
• V
DD12DSI
= 1.15 to 1.3 V: optional supply voltage for the DSI PHY (DSI regulator OFF)
• V
CAPDSI
: DSI regulator output
To achieve a better dynamic performance of the regulator, VCAPDSI pin must be
conn
ected to an external capacitor, which recommended value is 2.2 µF.
Additional precautions can be taken to filter analog noise:
• VDDA can be connected to V
DD
through a ferrite bead.
• The VREF+ pin can be connected to V
DDA
through a resistor (typically 47 Ω).
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