Application design robustness

AN2860

6/17

Doc ID 15267 Rev 5

2

Application design robustness

Even though the STM8 has been designed for a high level of EMC robustness, the user

should be aware that the modern high-density CMOS technology used for the STM8 design

is commonly and naturally noise sensitive.

This factor must be taken into account in users’ projects: this is important to avoid steps

which could lead to a degradation of the EMC robustness, especially in applications working

in an “aggressive” environment.

Some specific requirements and recommendations are given in the rest of this chapter.

2.1

Power supply

The STM8S and STM8AF product families are designed for standard applications in the

3.3 V to 5 V (+/-10%) supply voltage range.

the 1.8 V supply to the core and the peripherals. This pin must be decoupled with a

capacitance of at least 470 nF. If the capacitance of an applied capacitor drops under this

level due to temperature or lifetime changes or if a wrong capacitor value is connected, the

reset pin can toggle with a period of about 100 ms. To satisfy this minimum limit value, it is

recommended to use a capacitor with a higher capacitance (about 680 nF), taking into

account possible changes of this capacitance due to environment conditions and the period

of utilization.

provide a voltage from 2.5 V to 3.6 V to the built-in LCD drivers. An external capacitor from

0.1 to 2 µF must be connected to this pin to stabilize the LCD reference voltage.

present, must also be decoupled with a dedicated 100 nF capacitor.

Power supply connections are shown in the following diagrams.