An interface unit of a mobile device coupled to an auxiliary device, the interface unit including: a first plurality of switches configured for power delivery to the auxiliary device; at least one isolation unit coupled to the first plurality of switches, the at least one isolation unit configured to isolate the multiple signals and to prevent disruption of data communication between the mobile device and the auxiliary device; and a second plurality of switches configured for the data communication between the mobile device and the auxiliary device, the second plurality of switches configured to bypass the at least one isolation unit.