UM0970

Hardware and layout

Doc ID 17693 Rev 2

13/30

Figure 9.

ST-Link connections image

3.3

Power supply and power selection

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

power supply (5 V or 3.3 V). The D1 and D2 protection diodes allow the 5V and 3V3 pins to

be used independently as input or output power supplies (see Figure 3). The 5V and 3V3

pins can be used as an output power supply for use by an application board connected on

pin headers (P1 to P3). In such a case, the 3V3 pin provides only a 3V power supply and the

power consumption must be lower than 100 mA. The 5V and 3V3 pins can also be used as

an input power supply for the board when the USB connector is not connected to the PC.

Note:

If an external power supply is used, it must conform to EN 60950-1 SELV (safety extra low

voltage) LPS (limited power source) definitions.

If the 5V and 3V3 pins are used as an input power supply, the STM8L-DISCOVERY board

must be powered by a power supply unit or auxiliary equipment complying with standard

EN-60950-1: 2006+A11/2009, and must be safety extra low voltage (SELV) with limited

power capability.

3.4

LEDs

●

LD1 COM: Red LED indicates communication in progress between PC and ST-Link.

●

LD2 PWR: Red LED indicates that the board is powered.

●

LD3 PE7: Green LED is a user LED connected to the I/O PE7 of the STM8L152C6T6.

●

LD4 PC7: Blue LED is a user LED connected to the I/O PC7 of the STM8L152C6T6.

3.5

Push buttons

●

B1 RST: Push button is used to RESET the STM8L152C6T6.

●

B2 USER: User push button connected to the I/O PC1 of the STM8L152C6T6.

No jumpers on CN3