What distance can I measure using the Wake on Prox feature of the TouchXpress CPT devices?
Wake on proximity is very dependent on the layout and the configuration of the capacitive sensing electrodes with regard to pad design, drive strength, etc. It is recommended to characterize different electrodes and dielectric materials to determine the correct distance for a reliable proximity measurement. An example for proximity is to use an antenna design with minimal ground planes in proximity to the electrode. Either route the sensor with NO ground surrounding it or anywhere nearby, or add a wire to the design that routes inside the product case and connects to the PCB+CPT at a single point.
The TouchXpress tools (Capacitive Sense Profiler and TouchXpress Configurator) provide the ability to monitor the capacitive sensing parameters to dynamically characterize electrodes in the end system.