UM2179 datasheet(24/48 Pages) STMICROELECTRONICS

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Hardware layout and configuration

UM2179

24/48

UM2179 Rev 9

•

SMPS U16 allows to supply the VDD_MCU pins at 1.8 V with a maximum current of

50 mA. When SB125 is opened and SB120 closed, the SMPS can deliver higher

current but with higher consumption. This SMPS is disabled by default (See Table 10:

Configuration of the solder bridges and jumpers).

VDD_MCU solder bridge configuration:

•

3.3 V (default): SB122 closed, SB121 and SB127 open

•

1.8 V: SB122 open, and SB121 and SB127 closed (best ULPBench score)

Caution:

The power sequence is not respected when using 1V8 MCU_VDD. Refer to the Getting

started with STM32L4 Series and STM32L4+ Series hardware development application

note (AN4555), and to the corresponding STM32L4 Series and STM32L4+ Series product

datasheets.

Note:

The ST-LINK is still available in this configuration as a result of level shifter U14.

5.6

LEDs

User LD1: a green user LED is connected to the STM32 I/O PC7 (SB124 ON and SB123

OFF) or PA5 (SB123 ON and SB124 OFF) corresponding to the ST Zio D13. It only works

when VCC_MCU is 3.3 V.

User LD2: a blue user LED is connected to PB7.

User LD3: a red user LED is connected to PB14.

These user LEDs are on when the I/O is HIGH value, and are off when the I/O is LOW.

LD4 COM: the tricolor LED LD4 (green, orange and red) provides information about ST-LINK

communication status. LD4 default color is red. LD4 turns to green to indicate that the

communication is in progress between the PC and the ST-LINK/V2-1, with the following

setup:

•

Slow blinking red/off: at power-on before USB initialization

•

Fast blinking red/off: after the first correct communication between PC and

ST-LINK/V2-1 (enumeration)

•

Red LED on: when the initialization between the PC and ST-LINK/V2-1 is complete

•

Green LED on: after a successful target communication initialization

•

Blinking red/green: during communication with target

•

Green on: communication finished and successful

•

Orange on: communication failure

LD5 USB power fault: LD5 indicates that the board power consumption on USB exceeds

500 mA, consequently the user must power the board using an external power supply.

LD6 PWR: the green LED indicates that the STM32 part is powered and +5 V power is

available on CN8 pin 9 and CN11 pin 18.

LD7 and LD8 USB FS: refer to Section 5.12: USB FS OTG.

Note:1

LD1 is connected to U8 and it is driven by PC7 or PA5 which may be changed to 1.8 V I/O,

so LD1 cannot be lit when VDD is set to 1.8 V.

Note:2

LD2, LD3 cannot work with VDD_MCU= 1.8 V

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