UM2179 datasheet(21/48 Pages) STMICROELECTRONICS

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UM2179 Rev 9

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UM2179

Hardware layout and configuration

5.5

Power supply and power selection

The power supply is provided either by the host PC through the USB cable or by an external

source: VIN (7 V-12 V), E5V (5 V) or +3.3 V power supply pins on CN8 or CN11. If VIN, E5V

or +3.3 V is used to power a Nucleo-144 board, this power source must comply with the

standard EN-60950-1: 2006+A11/2009 and must be Safety Extra Low Voltage (SELV) with

limited power capability.

If the power supply is +3.3 V, the ST-LINK is not powered and cannot be used.

5.5.1

Power supply input from ST-LINK/V2-1 USB connector

The STM32 Nucleo-144 board and shield can be powered from the ST-LINK USB connector

CN1 (U5V), by placing a jumper between the pins 3 and 4 of JP6, as shown in Table 7:

Power related jumper. Note that only the ST-LINK part is power supplied before the USB

enumeration, as the host PC only provides 100 mA to the board at that time. During the

USB enumeration, the STM32 Nucleo-144 board requires 300 mA of current to the host PC.

If the host is able to provide the required power, the targeted STM32 microcontroller is

powered and the green LED LD6 is turned ON, thus the STM32 Nucleo-144 board and its

shield can consume a maximum current of 300 mA, not more. If the host is not able to

provide the required current, the targeted STM32 microcontroller and the extension boards

are not power supplied. As a consequence the green LED LD6 stays turned OFF. In such

case it is mandatory to use an external power supply as explained in the next section.

After the USB enumeration succeeds, 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 also features a current limitation to protect the PC if a short-circuit happens

on the board. If an overcurrent (more than 500 mA) happens on the board, the red LED LD5

lits up.

Warning:

If the maximum current consumption of the STM32 Nucleo-

144 board and its shield boards exceed 300 mA, it is

mandatory to power the STM32 Nucleo-144 board, using an

external power supply connected to E5V, VIN or +3.3 V.

Note:

If the board is powered by a USB charger, there is no USB enumeration, so the green LED

LD6 stays in OFF state permanently and the target STM32 is not powered. In this specific

case a jumper must be placed between pins 5 and 6 of JP6, to allow the board to be powered

anyway.

5.5.2

External power supply inputs

Depending on the used voltage, an external power source supplies in three different ways

the STM32 Nucleo-144 board and its shield boards. The three power sources are listed in

Table 6.

When the STM32 Nucleo-144 board is power supplied by VIN or E5V, the jumper configuration

must be as showed below:

•

Jumper JP6 on pin 1 and pin 2 for E5V or jumper JP6 on pin 7 and pin 8 for VIN

•

Jumper JP1 OFF

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