UM2411 Rev 2 15/61
UM2411 Hardware layout and configuration
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Table 3: Power-supply related jumper and solder bridge settings describes the settings of all
jumpers related to powering the STM32H747I-DISCO and extension board. VDD_MCU is
STM32H747XIH6 digital supply voltage line. It can be connected to a fixed 3.3 V supply.
5.2.1 Supplying the board through STLINK-V3E USB port
To power the STM32H747I-DISCO in this way, the USB host (a PC) gets connected to the
Micro-B USB receptacle of the STM32H747I-DISCO via a USB cable. The connection event
starts the USB enumeration procedure. In its initial phase, the host USB port current supply
capability is limited to 100
mA. It is enough because only the STLINK-V3E part of the
STM32H747I-DISCO draws power at that time: the U10 STMPS2151 power switch is set to
the OFF position, which isolates the rest of the STM32H747I-DISCO from the power source.
In the next phase of the enumeration procedure, the host PC informs the STLINK-V3E
facility of its capability to supply current up to 300
mA. If the answer is positive, the STLINK-
V3E sets the U10 STMPS2151 switch to the ON position to supply power to the rest of the
STM32H747I-DISCO board. If the PC USB port is not capable of supplying current up to
300
mA of, CN8 pin8 (VIN) or CN14 can be used to supply the board instead.
Should a short-circuit occur on the board, the STMPS2151 power switch protects the USB
port of the host PC against a current demand exceeding 500
mA, In such an event, the LD9
LED lights up.
The STM32H747I-DISCO board can also be supplied from a USB power source not
supporting enumeration, such as a USB charger. In this particular case, jumper JP6 must be
fitted with a jumper hat as shown in
Table 3: Power-supply related jumper and solder bridge
settings. STLINK-V3E bypasses STMPS2151 power regardless of enumeration procedure
result and passes the power unconditionally to the board.
The LD8 green LED turns on whenever the whole board is powered.
5.2.2 Using STLINK-V3E along with powering through external power
It can happen that the board requires more than 300 mA of supply current. It cannot be
supplied from the host PC connected to the STLINK-V3E USB port for debugging or
programming the STM32H747XIH6. In such a case, the board can be supplied through CN8
pin8 (marked VIN on the board) or CN14.
To do this, it is important to power the board before connecting it with the host PC, which
requires the following sequence to be respected:
1. Set jumper JP6 in the E5V or U5V position
2. Connect the external power source to CN8 pin8 or CN14
3. Check that the green LED LD8 is turned on
4. Connect the host PC to USB connector CN2
Caution: In case the board demands more than 300 mA and the host PC is connected via USB
before the board is powered from CN8 pin8 or CN14, there is a risk that the following events
occur (listed in reverse severity order):
1. The host PC is capable of supplying 300 mA (the enumeration succeeds) but it
features no over-current protection on its USB port. It is damaged due to over-current.
2. The host PC is capable of supplying 300 mA (the enumeration succeeds) and it has a
built-in over-current protection on its USB port, limiting or shutting down the power out
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