Hardware layout and configuration
UM2036
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DocID029088 Rev 3
6.2 Power
supply
The STM32F779I-EVAL evaluation board is designed to be powered by the 5 V DC power
supply and to be protected from wrong power plug-in event by PolyZen. It is possible to
configure the evaluation board to use any of the following power supply six sources:
•
5 V DC power adapter connected to CN19 (JP20 jumper in position PSU). This is
default setting of power supply source selection on STM32F779I-EVAL evaluation
board.
•
5 V DC power with 500mA limitation from CN22 (JP20 jumper in position STLK) (the
USB Micro-B connector of the ST-LINK/V2-1 that is showed as STLK on JP20
silkscreen and called U5V). If the USB enumeration succeeds (as explained below),
the ST-LINK U5V power is enabled, by asserting the PWR_EN pin. This pin is
connected to a power switch (ST890), which powers the board. This power switch
features also a current limitation to protect the PC in case of short-circuit. If overcurrent
(more than 600 mA) happens on the board, the LED LD11 is lit.
•
5 V DC power with 500 mA limitation from CN8 (the USB OTG2 HS Micro-AB
connector (JP20 jumper in position HS).
•
5 V DC power with 500 mA limitation from CN13, the USB OTG1 FS Micro-AB
connector (JP20 jumper in position FS1).
•
5 V DC power with 500 mA limitation from CN14, the USB OTG2 FS Micro-AB
connector (JP20 jumper in position FS2).
•
5 V DC power from CN5 and CN6 (JP20 jumper in position D5V).
The STM32F779I-EVAL evaluation board can be powered from ST-LINK USB Micro-B
connector CN22 (U5V), but only the ST-LINK circuit has the power before USB enumeration
starting, because the host PC only provides 100 mA to the boards at that time. During the
USB enumeration, the STM32F779I-EVAL board asks for the 300 mA power from the host
PC. If the host is able to provide the required power, the target STM32 is powered and the
red LED LD10 is turned on, thus the STM32F779I-EVAL board can consume maximum
300 mA current, but not more. If the host is not able to provide the requested current, the
enumeration fails. Therefore the STM32 part including the extension board will not be
powered. As a consequence the red LED LD10 remains turned off. In this case it is
mandatory to use an external power supply as an extra power supply.
E5V (from PSU) or D5V must be used as external power supply in case current
consumption of STM32F779I-EVAL board exceeds the allowed current on USB. In this
condition it is still possible to use USB for communication, for programming or debugging
only, but it is mandatory to power the board first using E5V or D5V, and then connecting the
USB cable to the PC. Proceeding this way, ensures that the enumeration succeeds thanks
to the external power source.
The following power sequence procedure must be respected:
1.
Connect jumper JP20 for PSU or D5V side
2. Check that JP27 is removed
3. Connect the external power source to PSU or D5V (daughterboard mounted)
4. Check that the red LED LD10 is turned ON
5. Connect the PC to USB Micro-B connector CN22
If this order is not respected, the board may be powered by VBUS first, then by E5V or D5V,
and the following risks may be encountered:
