Various embodiments include apparatus, systems, and methods having a conductive contact configured to couple to a resistor-capacitor (RC) network, a device unit coupled to the conductive contact, and a mode switching unit to change a characteristic of a signal at the conductive contact based at least in part on an RC time constant of the RC network. The mode switching unit may switch the device unit between a first operating mode and a second operating mode based on a signal level of the signal.