2.3 Touch Sensor

The sensor electrodes are connected to the BUTTONx pins of the MTCH2120 touch controller via series resistors to reduce electromagnetic interference (EMI) and electromagnetic compatibility (EMC), following the guidelines of the AN2924 "Capacitive Touch Sensor Design Guide" application note.

The series resistors used in this evaluation kit are 100 kΩ each, with a variance of 10-200 kΩ in a real-world application, depending on the sensor capacitance and desired level of EMC performance. For more details, refer to the "Capacitive Touch Sensor Design Guide" application note.

The MTCH2120 Evaluation Kit has been tested against conducted immunity according to IEC 61000-4-6 and passes the test at the highest level 3 (10 V_rms Conducted immunity noise). No False touch is observed, and touch detection works as expected. The default MTCH2120 parameters are used for the test. Refer to the MTCH2120 Data sheet for default parameters.