ST Nucleo-64 STM32U3 User Manual page 19

STLK is a 5 V DC power with limitations from the STLINK-V3EC USB connector (CN1). In this case, the 5V
jumper selection (JP3) must be on pin [1-2] to select the STLK power source on the JP3 connector. This is the
default setting. If the USB enumeration succeeds, the STLK power is enabled, by asserting the T_PWR_EN
signal from STLINK-V3EC. This pin is connected to the overvoltage protection (U5) with maximum current
management.
STLINK-V3EC USB connector (CN1) can power the Nucleo-64 board and its shield. Nevertheless, only the
STLINK-V3EC circuit is powered before USB enumeration because the host PC only provides 100 mA to the
board at that time. During the USB enumeration, the Nucleo-64 board requests 500 mA power from the host PC.
• If the host can provide the required power, the U5 power switch is enabled, the green LED (LD3) is turned
ON, and the Nucleo-64 board and its shield can consume up to 500 mA.
• If the host is not able to provide the requested current, the enumeration fails. The U5 power switch remains
OFF and the MCU part including the extension board is not powered. As a consequence, the green LED
(LD3) remains OFF. In this case, it is recommended to use an external 5 V power source.
STLK configuration: 5V jumper selection JP3[1-2] must be connected as shown in
UM3062 - Rev 2
Figure 10. 5V jumper selection JP3[1-2]: STLK power source
STM32
microcontroller
UM3062
Hardware layout and configuration
Figure 10.
USB STLINK-V3EC
(CN1)
5V LED
(LD3)
5V_STLK selection
(JP3 [1-2])
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