AN4038 datasheet(6/39 Pages) STMICROELECTRONICS

6 / 39 page

Test setup overview

AN4038

6/39

Doc ID 022686 Rev 1

Environmental variation

●

Variation in the power supply level can disrupt the sensor measurement and cause

unwanted proximity detection.

●

Temperature and humidity variations modify the electrical field of the sensor and affect

the proximity detection range.

●

Designers with applications which are influenced by one of these parameters and

which are susceptible to large variation should consider and evaluate the impact on the

proximity sensing solution. The system should guarantee the stability of the detection

to avoid any false detection.

Special care should be taken of the above factors to ensure stability of the systems.

Excessive increase of a sensor’s sensitivity can cause an unstable system and trigger

unwanted proximity detection.

Test setup overview

All information provided in this application note is based on tests performed using different

hardware boards.

2.1

Sensor performance measurements

The sensor performance measurements presented below were made using very basic

sensors. These sensors were designed so that only one parameter was changed in each

test series (length, width, clearance gap, etc). In this way, the influence of the ‘control’

parameter was clearly evaluated.

The sensors used for the tests are shown in Figure 1, Figure 2, Figure 3, and Figure 4.

During testing, the sensors were connected to an STM8TL5xxx controller board:

MCD10-016.

Figure 1.

Sensor board - Tx/Rx electrode spacing test

AN4038 Datasheet(PDF) 6 Page - STMicroelectronics