Power Supply And Power Selection; Figure 8. St-Link/V2-1 Connections - ST STM32F334C8 User Manual

Hardware layout
5.2

Power supply and power selection

The power supply is provided either by the host PC through the USB cable, or by an
external 5 V power supply.
The STM32F334 Discovery board requires 500 mA from the host PC but around 300 mA is
needed for its demo, 100 mA for an extension board, and a safety margin of 100 mA.
The D2 and D3 diodes protect the 5 V pins from external power supplies:
•
5 V and 3 V can be used as output power supplies when an extension board is
connected to pins P1 and P2.
In this case, the 5V_O and 3V_O pins deliver a 5 V or 3.3 V power supply and the
power consumption of the extension board must be lower than 100 mA.
•
5 V can also be used as an input power supply, for example, when the USB connector
is not connected to the PC. (5V_I pin of P1 header)
In this case, a power supply unit or auxiliary equipment complying with the EN-60950-
1: 2006+A11/2009 standard must power the STM32F334 Discovery board and must be
safety extra low voltage (SELV) with limited power capability.
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Figure 8. ST-LINK/V2-1 connections

UM1735 Rev 3
UM1735