Overview
Description
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.
Self-Capacitance Water-Resistant Button and Electrode Board
- Based on the high-sensitivity, high-noise-tolerance Renesas capacitive touch key solution
- Example of CTSU2 active shielding
- Self-capacitance touch buttons achieve both water resistance and noise immunity
- Complies with IEC 61000 4-3 Level 3 for radiated noise immunity
- Applicable to a variety of products requiring water resistance, including white goods, bathroom appliances, and outdoor equipment
| Desired Feature | Technology Issue |
|---|---|
| When you'd like to adopt a capacitive touch button to a device that will be used in a wet environment, such as a kitchen | It is possible to mis-detect with water drops in the conventional self-capacitance touch method |
| When you'd like to improve noise immunity | It is possible to mis-detect with water drops if using a GND shield |
| When you'd like to configure with a simple electrode pattern | It will be a complex electrode design if using a mutual-capacitance method, which has the water resistance |
This design can resolve these issues: It enables improving the water resistance with an active shield, as the self-capacitance method is a simpler electrode design, as well as keeping noise immunity.
As a reference design, Renesas publishes application notes, sample code, and hardware design files, allowing you to start development immediately.
* The active-shield function is supported on the MCU included CTSU2 IP.
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
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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.