SB1 is configured according to the maximum current consumption of the board. SB1 can be set to on to inform
the host PC that the maximum current consumption does not exceed 100 mA (even when the Arduino
™
Nano
shield is plugged). In such condition, USB enumeration always succeeds since not more than 100 mA is
requested to the host PC. Possible configurations of SB1 are summarized in
Table 5.
SB1 configuration
Solder bridge state
Power supply
Allowed current
SB1 OFF (default)
USB power through CN1
300 mA max
SB1 ON
100 mA max
SB1 (ON/OFF)
VIN, +3V3 or +5V power
For current limitation, refer to
Attention:
If the maximum current consumption of the STM32G0 Nucleo-32 board and its shield board exceeds 300 mA, it
is mandatory to power the STM32G0 Nucleo-32 board by means of an external power supply connected to VIN,
+5V or +3V3.
Note:
In case the board is powered by a USB charger, there is no USB enumeration. LED LD2 remains off
permanently and the target STM32 is not powered. In this specific case, the SB1 must be set to on, to allow the
target STM32 to be powered anyway.
6.4.2
External power supply inputs
The STM32G0 Nucleo-32 board and its shield board can be powered in three different ways from an external
power supply, depending on the voltage used. The three power sources are summarized in the
Table 6.
External power sources
Input power
name
Connector
pin
Voltage range
Max current
Limitation
VIN
CN4 pin 1
7 V to 12 V
800mA
From 7 V to 12 V only and input current capability is
linked to input voltage:
•
800 mA input current when VIN = 7 V
•
450 mA input current when 7 V < VIN < 9 V
•
300 mA input current when 10 V > VIN > 9 V
•
less than 300 mA input current when VIN > 10 V
+5V
CN4 pin 4
4.75 V to 5.25 V
500mA
-
+3V3
CN4 pin 14
3 V to 3.6 V
-
ST-LINK not powered and SB2 and SB3 must be OFF.
VIN or +5V power supply
When powered from VIN or +5 V, it is still possible to use ST-LINK for communication for programming or
debugging only, but it is mandatory to power the board first, using VIN or +5 V, then to connect the USB cable to
the PC. By this way the enumeration succeeds anyway, because of the external power source.
The following power sequence procedure must be respected:
1.
Check that SB1 is OFF
2.
Connect the external power source to VIN or +5V
3.
Power on the external power supply 7 V < VIN < 12 V to VIN, or 5 V for +5V
4.
Check that red LED LD2 is turned on
5.
Connect the PC to USB connector CN1
If this order is not respected, the board may be powered by VBUS first, then by VIN or +5V, and the following risks
may be encountered:
UM2591
Power supply
UM2591
-
Rev 1
page 12/26
