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UM1775 Hardware layout
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Figure 7. ST-LINK/V2-1 connections
6.2 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 STM32L053 Discovery board requires 300 mA from the host PC: about 90 mA are
needed by a simple E-paper demo application, 100 mA for an extension board, and 100 mA
as a safety margin.