ST STM32F0 Series Application Note

5.7 Noise
Noise is a key point for touch sensing applications. Noise can come from Power supply.
5.7.1 Power supply
Main rules to follow:
• Place Buzzer and LED before LDO.
• Place LDO close to MCU.
Figure 20. Typical power supply schematic
Supply
input
LDO
regulator
(1)
V
IN
V
OUT
V
SS
1 μF 100 μF 100 μF 1 μF
Touch sensing
device (MCU)
V
DD
V
DD
LEDs
V
DD
V
SS
GPIO
LED
10 nF
Table 14. Power supply documentation gives a list of documents containing information about the power supply.
Table 14. Power supply documentation
Id
Title Chapters
AN4312
Guidelines for designing touch sensing applications
with surface sensors
Power supply
5.7.2 False detection
To avoid false detection TSL embed ECS, DXS and DTO algorithms.
Table 15. False detection documentation gives a list of documents containing information about the false
detection.
Table 15. False detection documentation
Id Title Chapters
UM1913
Developing applications on STM32Cube with
STMTouch® touch sensing library
• Environment Change System (ECS)
– Power supply voltage, temperature and
air humidity
• Detection Exclusion System (DXS)
• Detection Time Out (DTO)
AN5105
Noise
AN5105 - Rev 1
page 21/52

ST STM32F0 Series Specifications

General

Brand	ST
Model	STM32F0 Series
Category	Microcontrollers
Language	English