UM2408 Rev 1
19/45
UM2408
Hardware layout and configuration
44
Figure 8. Power supply input from ST-LINK USB connector with PC (5 V, 500 mA max)
If the USB enumeration succeeds, the 5V_ST_LINK power is enabled, by asserting the
PWR_ENn signal from STM32F723IEK6 "STLINK V3" (U7). This pin is connected to a
power switch STMPS2151STR (U2), which powers the board. The power switch
STMPS2151STR (U2) features also a current limitation to protect the PC in case of short-
circuit on board. If an overcurrent (more than 500 mA) happens on board, the red LED LD6
is lit.
Nucleo board and its shield on it can be powered from ST-LINK USB connector CN1, but
only ST-LINK circuit gets power before USB enumeration, because the host PC only
provides 100 mA to the board at that time.
During the USB enumeration, Nucleo board asks for the 500 mA power to the host PC.
•
If the host is able to provide the required power, the enumeration finishes by a
"SetConfiguration" command and then, the power switch STMPS2151STR is switched
ON, the Green LED LD5 is turned ON, thus Nucleo board and its shield on it can
consume 500 mA current, but not more.
•
If the host is not able to provide the requested current, the enumeration fails.
Therefore, the STMPS2151STR power switch (U2) remains OFF and the MCU part
including the extension board is not powered. As a consequence, the GREEN LED
LD5 remains turned OFF. In this case it is mandatory to use an external power supply.
6.4.2 External
power
supply input from V
IN
(7-11 V, 800 mA max)
When STM32H7 Nucleo-144 board is power supplied by V
IN
(see
and
), the
jumper configuration must be the following: Jumper JP2 on pin 3-4 "VIN"
