MIPI-10 pin STDC14 pin CN8 Designation
7 9 T_JRCLK
Not used by SWD protocol, Target JRCLK (T_JRCLK) using JTAG protocol,
only for specific use
8 10 T_JTDI
Not used by SWD protocol, Target JTDI (T_JTDI) using JTAG protocol, only
for external tools
9 11 GNDDetect GND detect for plug indicator, used on SWD and JTAG neither
10 12 T_NRST
Target NRST using SWD protocol or Target JTMS (T_JTMS) using JTAG
protocol
- 13 T_VCP_RX Target RX used for VCP (must be UART dedicated to bootloader)
- 14 T_VCP_TX Target TX used for VCP (must be UART dedicated to bootloader)
8.2 Power supply
The STM32H7B3I-DK Discovery kit is designed to be powered from 5 V DC power source.
One of the following 5 V DC power inputs can be used, upon an appropriate board configuration:
• A host PC connected to CN14 through a USB Micro-B cable with enumeration (default setting)
• An external charger connected to CN14 through a USB Micro-B cable (without enumeration)
• An external 7-12V power supply connected to CN19 pin 8 (ARDUINO
®
)
• A host PC connected to CN15 through a USB Micro-AB cable (5V_USB_HS)
• An external 5V power supply connected to CN2 (E5V)
The LD5 green LED turns ON when the voltage on the power line marked 5V is present. All supply lines required
for the operation of the components on the STM32H7B3I-DK are derived from that 5V line.
Note: The Discovery board must be powered by a power supply unit, or by auxiliary equipment complying with the
standard EN-60950-1: 2006+A11/2009, and must be Safety Extra Low Voltage (SELV) with limited power
capability.
8.2.1 Supplying the board through STLINK-V3E USB connector 5 V / 500 mA
The STM32H7B3I-DK Discovery kit can be powered from the STLINK-V3E connector CN14, by placing a jumper
between the pins 1-2 of JP1 “STLK”. This is the default setting.
If the USB enumeration succeeds, the 5V_ST_LINK power is enabled, by asserting the PWR_ENn signal from
STM32F723IEK6 “STLINK V3” (U18). This pin is connected to a power switch STMPS2151STR (U24), which
powers the board. The power switch STMPS2151STR (U24) features also a current limitation to protect the PC in
case of short-circuit on the board. If an overcurrent (more than 500mA) occurs onboard, the RED LED LD7 is lit.
The STM32H7B3I-DK board with its shield can be powered from the STLINK-V3E USB connector CN14, but only
ST-LINK circuit gets power before USB enumeration because the host PC only provides 100mA to the board at
that time.
During the USB enumeration, the STM32H7B3I-DK board asks for 500mA 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 the
STM32H7B3I-DK board and its shield on it can consume 500mA current, but no more.
• If the host is not able to provide the requested current, the enumeration fails. Therefore, the
STMPS2151STR power switch (U24) 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.
UM2569
Power supply
UM2569 - Rev 1
page 14/54
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