Minimizing energy consumption in capacitive sensing applications

Minimizing energy consumption in capacitive sensing applications

Capacitive sensing is all about the ability to measure the capacitance, or more often the change in capacitance, between two or more electrodes. As a technique it is frequently employed to detect proximity or position but can also be used to measure humidity, fluid level and acceleration. Because capacitive sensing supports such a diverse range of applications, solutions are found in many different markets from industrial, automotive and medical through to consumer. And as more and more electronic products are being designed with touchpads and touchscreens we are seeing an explosion in the use of capacitive sensing technology to provide the vital human machine interface (HMI).

Along with this dramatic uptake in the use of capacitive sensing, there is an increasing consciousness in the environmental aspects of product design. So while the use of capacitive sensing to replace mechanical switches may increase the reliability and hence the life expectancy of a product this benefit could be negated by the increased energy consumption of the electronic circuits needed to continually monitor the sensor inputs. This white paper looks at a number of capacitive sensing applications to understand how they operate and the benefits they offer over alternative solutions. It then goes on to consider how concerns regarding energy consumption can be mitigated using a microcontroller (MCU) that can remain in an ultra-low power, deep-sleep mode while still being able to detect and respond to sensor inputs quickly and reliably.■