External Power Supply Input From Vin (7 To 12 V, 800 Ma Max); Figure 10. Power Supply Input From Stlink-V3E Usb Connector With Pc (5 V, 500 Ma Max) - STMicroelectronics STM32H7 User Manual

Hardware layout and configuration

Figure 10. Power supply input from STLINK-V3E 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-V3E' (U7). This pin is connected to a
power switch (U2), which powers the board. The power switch (U2) features also a current
limitation to protect the PC in case of short-circuit onboard. If an overcurrent (more than
500 mA) happens onboard, the red LED (LD6) is lit.
The STLINK-V3E USB connector (CN1) can power the Nucleo board with its shield.
However, the STLINK-V3E circuit gets power before USB enumeration because the host PC
only provides 100 mA to the board at that time.
During the USB enumeration, the Nucleo board asks for 500 mA power to the host PC.
•
If the host can provide the required power, the enumeration finishes with a
SetConfiguration command. Then, the power switch and the green LED (LD5) are
turned ON. Thus, the Nucleo board and its shield can consume 500 mA current, but no
more.
•
If the host is not able to provide the requested current, the enumeration fails.
Therefore, the 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.
Warning:
6.4.2

External power supply input from VIN (7 to 12 V, 800 mA max)

When the STM32H7 Nucleo-144 board is power supplied by VIN (refer to
Figure 11), the jumper (JP2) configuration must be [3-4] VIN.
20/49
U7
STM32F723
STLINK-V3
3V3
In case the maximum current consumption of the STM32H7
Nucleo-144 board and its shield boards exceed 300 mA, it is
mandatory to power the STM32H7 Nucleo-144 board, using
an external power supply connected to E5V, V
UM2407 Rev 3
PC
CN1
U2
5V
3V3
UM2407
MSv61203V2
, or +3.3 V.
IN
Table 6 and