Short detection circuit

A circuit, comprising:

• an output adapted to be coupled to a conductor with an expected resistance;
• a first pull-up network adapted to be coupled to voltage supply and to the output and configured to include a first resistance;
• a second pull-up network adapted to be coupled to the voltage supply and to the output and configured to include a second resistance;
• and
• a comparator having a first input terminal coupled to the output, a second input terminal configured to receive a reference voltage, and an output terminal configured to output a comparison result;
• wherein the circuit indicates a fault when the first resistance is greater than the resistance between the output and a ground terminal, and wherein the circuit indicates a high-impedance state exists when the second resistance is less than the resistance between the output and the ground terminal.

A circuit, comprising:

• an output adapted to be coupled to a conductor with an expected resistance;
• a first pull-up network adapted to be coupled to a voltage supply and to the output and configured to include a first resistance;
• a second pull-up network adapted to be coupled to the voltage supply and to the output and configured to include a second resistance;
• and
• a comparator having a first input terminal coupled to the output, a second input terminal configured to receive a reference voltage, and an output terminal configured to output a comparison result;
• wherein a fault exists when the first pull-up network is active and the voltage for transmission is less than a reference voltage a predetermined period of time after the first pull-up network became active, and wherein a high-impedance state further exists when the second pull- up network is active and the voltage for transmission is greater than the reference voltage a predetermined period of time after the second pull-up network became active.

A circuit, comprising:

• an output adapted to be coupled to a conductor with an expected resistance;
• a first pull-up network coupled between a voltage supply input and the output, the first pull-up network having a first resistance;
• a second pull-up network coupled between the voltage supply input and the output, the second pull-up network having a second resistance;
• and
• a comparator having a first input terminal coupled to the output, a second input terminal configured to receive a reference voltage, and an output terminal;
• further comprising:
• a first resistor coupled between the voltage supply input and a first node;
• a second resistor coupled between the first node and the output;
• and
• an amplifier having a first input terminal coupled to the first node, a second input terminal configured to receive a common mode voltage associated with the differential conductor, and an output terminal coupled to the output.

A method, comprising:

• receiving a common mode voltage on which a transmission on a differential conductor is at least partially based;
• enabling a first pull-up network coupled to the differential conductor;
• generating a comparison result indicating a presence of a fault on the differential conductor, by comparing a voltage present at the differential conductor to a reference voltage after a first period of time, when a resistance of the pull- up network is greater than a resistance associated with the differential conductor;
• and
• generating the comparison result indicating no fault on the differential conductor, by comparing the voltage present at the differential conductor to the reference voltage, when the resistance of the pull-up network is less than the resistance associated with the differential conductor.

A system, comprising:

• a transmitter comprising a fault detection circuit that comprises:
• an output;
• a first pull-up network coupled between a voltage supply and the output;
• a second pull-up network coupled between the voltage supply node and the output;
• and
• a comparator having a first input terminal coupled to the output, a second input terminal configured to receive a reference voltage, and an output terminal configured to output a comparison result;
• a receiver comprising a termination circuit;
• and
• a differential conductor, comprising:
• a positive conductor coupling the output to the receiver and configured to couple to the fault detection circuit and the termination circuit;
• and
• a negative conductor coupling the transmitter to the receiver and configured to couple to the fault detection circuit and the termination circuit.