Overview
Description
Capacitive touch buttons used in wet environments, such as kitchen appliances, can suffer from false detections caused by water droplets when using conventional self-capacitance sensing. While a GND shield can improve noise immunity, it may still be susceptible to water-induced misdetections. Mutual-capacitance sensing offers better water resistance, but requires a more complex electrode design.
The Renesas capacitive sensor, CTSU2, can utilize an active shield without any external components. Active shielding is effective in improving water resistance as well as improving the noise immunity of self-capacitance buttons.
The Self-Capacitance Waterproof Button Solution reference design compares the water resistance of traditional GND shields to the active shield for the self-capacitance buttons. This design addresses these challenges by improving water resistance through active shielding while maintaining the simple electrode design of the self-capacitance method and preserving noise immunity.
Features
- 8 Self-Capacitance Touch Buttons (4 GND Shields, 4 Active Shields)
- 4 GND Shield Buttons: 4
- 4 Active Shield Buttons: 4
- 8 LED Indicators: 8
- Based on the high-sensitivity, high-noise-tolerance Renesas capacitive touch key solution
- Supports active shielding through the MCU-integrated CTSU2 IP
- Self-capacitance touch buttons achieve both water resistance and noise immunity
- Complies with IEC 61000 4-3 Level 3 for radiated noise immunity
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The capacitive touch sensing unit "CTSU2" has enhanced noise immunity functions and supports "active shields." It is also effective in improving the water resistance of self-capacitance touch buttons. In this demo, a GND shield and an active shield have been placed to compare the water resistance of each shielding method.
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