Capacitive Touch Liquid Level Indicator Reference Design

This reference design measures the water level with a one-channel self-capacitance electrode and a one-channel shield electrode using a Renesas capacitive touch key solution. Electrodes and liquid tanks need to be GND shielded with conductors, but the linear values can be measured with one channel of self-capacitance electrodes.

Problems with conventional water level measurement technology (float type, weight sensor) are solved with Renesas' Capacitive Sensor Application Reference Design. When considering water level detection via float, many physical components are susceptible to damage due to fatigue and deterioration of parts, due to high costs. Additionally, when considering water level detection via a weight sensor, high costs can be incurred due to sensor elements and peripheral circuits.

With Renesas' water level measurement, parts are virtually free from fatigue and wear and tear; they are very hard to break. For systems that use a microcontroller, replacing the microcontroller and adding electrodes is all that is needed, and the cost to do this is low. Finally, touch key and water level measurement can be achieved simultaneously.