There is provided a system for transmitting power and data from a host device to a receiver device over an electrical connection, including a host device configured to transmit power and data through an output, and configured to transmit the power through the output at different times to the data; a receiver device having an input connectable to the output of the host device, the receiver device including a power receiving circuit, a data receiving circuit, and a switch element configured to connect the input to the power receiving circuit or the data receiving circuit dependent on a voltage of a signal received from the input. There is also provided a receiver device for receiving power and data from the host device.