Abstract: A power and data transfer system includes a portable device with a first contact circuit formed from a pair of contact pads having an outer surface covered with a dielectric material. A processing unit is coupled to the first contact circuit. A host unit has a second contact circuit including a second pair of contact pads which are also covered with a dielectric material. A host processing unit is coupled to the second contact circuit. The first and second contact circuits are adapted to form a capacitive interface when the portable device is positioned proximate the host unit. The capacitive interface transmits power signals from the host unit to the portable device. The same contacts are used to transmit bi-directional data signals between the portable device and the host unit.