Designing a Capacitive Sensing System for a Specific Application

Capacitive sensing buttons are emerging as a popular interface alternative to mechanical switches in many consumer electronics and white goods applications. However, designing a capacitive sensing interface comes with its own challenges that introduce new product development, production, and quality control concerns. For example, the parasitic capacitance (CP) of capacitive sensing buttons can vary from board to board and also can vary due to environmental changes like change in temperature and humidity. Noise also varies from system to system. Another common issue with user interface (UI) design is design portability. If the UI design of a TV front panel changes, for example, the design will require sensor retuning to accommodate changes in layout, sensor dimensions, etc. The laborious process of tuning adds cost to a system in terms of manpower and time, as well as delays the product’s time to market. This article focuses on different hurdles faced when designing a capacitive sensing interface and methods developers can use to overcome typical problems to make a design robust and portable.