Medical and industrial applications often require galvanic isolation of 2500VAC or higher for the safety of patients and equipment operators. The isolation barrier conveys not only power to the sensing element, but also data to or from that element. Each data signal crossing the barrier requires isolation, so one typically saves costs in these applications by choosing a serial bus rather than a parallel bus. This application note discusses an interface circuit that uses the Dallas Semiconductor 1-Wire serial bus to provide isolated power and bidirectional communications between a master (MCU) and a sensing element.