Patent ID: 8725910

Claim:
A cable detection circuit for a device coupled to a communication interface, the cable detection circuit comprising: a generator circuit comprising a first current source to inject current into a line of the communication interface through a first switch and a second current source to sink current from the line of the communication interface through a second switch, wherein the generator circuit is operative to provide currents on the line of the communication interface after removing residual voltage present on the line; a voltage discharger coupled by an external switch to the line of the communication interface, wherein the voltage discharger is coupled through the second switch to the second current source to remove all residual voltage present on the line before the generator circuit provides currents on the line; and a controller coupled to the generator circuit and operative to detect an amount of capacitance on the line based on the provided currents, wherein the controller is operative to provide an output based on the detected amount of capacitance, the output indicating whether a cable is connected to the device via the communication interface.