STMicroelectronics Nucleo Development Board for STM32 Microcontrollers NUCLEO-F103RB NUCLEO-F103RB Datenbogen

DocID025833 Rev 3

          

VIN or E5V can be used as external power supply in case the current consumption of 
NUCLEO and extensions boards exceeds the allowed current on USB. In this condition it is 
still possible to use the USB for communication, for programming or debugging only, but it is 
mandatory to power supply the board first using VIN or E5V then connect the USB cable to 
the PC. Proceeding this way ensures that the enumeration occurs thanks to the external 
power source. 

The following power sequence procedure must be respected: 
1.

Connect the jumper between pin 2 and pin 3 of JP5. 

2.  Check that JP1 is removed.
3.  Connect the external power source to VIN or E5V.
4.  Power on the external power supply 7

 

V< VIN < 12

 

V to VIN, or 5

 

V for E5V.

5.  Check that LD3 is turned ON.
6.  Connect the PC to USB connector CN1.

If this order is not respected, the board may be supplied by VBUS first then by VIN or E5V, 
and the following risks may be encountered:
1.

If more than 300

 

mA current is needed by the board, the PC may be damaged or the 

current supply can be limited by the PC. As a consequence the board is not powered 
correctly.

2. 300

 

mA is requested at enumeration (since JP1 must be OFF) so there is risk that the 

request is rejected and the enumeration does not succeed if the PC cannot provide 
such current. Consequently the board is not power supplied (LED LD3 remains OFF).

JP5

U5V (STLINK VBUS) is used as power source when JP5 is set as shown below 
(Default setting)

VIN or E5V is used as power source when JP5 is set as shown below.







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