Open-circuit sensors utilizing inductive coupling

An inductive open-circuit sensor comprising:

• a conductor having a relay, wherein the relay has a closed state allowing current flow within the conductor and an open state preventing current flow within the conductor, and wherein the conductor includes a coil portion disposed within an integrated circuit (IC) package;
• a first transmitting coil disposed on an IC die within the IC package and configured to produce a reference magnetic field at a reference frequency in response to receiving a drive current, wherein the reference magnetic field is configured to produce an induced current in the coil portion of the conductor when the relay is in a closed state;
• a first coil driver disposed within the IC package and configured to produce the drive current and provide the drive current to the first transmitting coil;
• magnetoresistance circuitry disposed within the IC package and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by the induced current when present and produce an output signal corresponding to the net magnetic field;
• and
• a main signal path connected to the magnetoresistance circuitry configured to receive the output signal, wherein the main signal path is configured to determine, based on the out output signal, whether the relay is in a closed or an open state,
• wherein the conductor is configured to conduct current having a frequency in a first frequency band, wherein the reference frequency of the reference magnetic field is within the first frequency band, and wherein the reference frequency is produced with a spread spectrum sequence.

An inductive open-circuit sensor comprising:

• a conductor having a relay, wherein the relay has a closed state allowing current flow within the conductor and an open state preventing current flow within the conductor, and wherein the conductor includes a coil portion disposed within an integrated circuit (IC) package;
• a first transmitting coil disposed on an IC die within the IC package and configured to produce a reference magnetic field at a reference frequency in response to receiving a drive current, wherein the reference magnetic field is configured to produce an induced current in the coil portion of the conductor when the relay is in a closed state;
• a first coil driver disposed within the IC package and configured to produce the drive current and provide the drive current to the first transmitting coil;
• magnetoresistance circuitry disposed within the IC package and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by the induced current when present and produce an output signal corresponding to the net magnetic field;
• a main signal path connected to the magnetoresistance circuitry configured to receive the output signal, wherein the main signal path is configured to determine, based on the out output signal, whether the relay is in a closed or an open state;
• and
• a feedback loop including a second transmitting coil and a second coil driver, wherein the feedback loop is configured to receive the output signal from the main signal path and produce a feedback magnetic field at the reference frequency, and wherein the magnetoresistance circuitry is configured to detect the net magnetic field as a combination of the reference magnetic field, the induced magnetic field when present, and the feedback magnetic field.

A method of detecting an open circuit state of a conductor using an inductive sensor, wherein the conductor includes a relay, wherein the relay has a closed state allowing current flow within the conductor and an open state preventing current flow within the conductor, the method comprising:

• with a first transmitting coil disposed on an integrated circuit (IC) die within an IC package, producing a reference magnetic field at a reference frequency in response to receiving a drive current, wherein the reference magnetic field is configured to produce an induced current in the conductor when the relay is in the closed state;
• with a first coil driver disposed within the IC package, producing the drive current and providing it to the first transmitting coil;
• with magnetoresistance circuitry disposed within the IC package and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by the induced current when present, producing an output signal corresponding to the net magnetic field;
• and
• with a main signal path connected to the magnetoresistance circuitry and configured to receive the output signal, determining whether the relay is in the closed state or the open state, wherein the inductive sensor includes a feedback loop including a second coil and a second coil driver, wherein the feedback loop is configured to receive the output signal from the main signal path and produce a feedback magnetic field at the reference frequency, and wherein the magnetoresistance circuitry is configured to detect the net magnetic field as a combination of the reference magnetic field, the induced magnetic field when present, and the feedback magnetic field.

A method of detecting an open circuit state of a conductor using an inductive sensor, wherein the conductor includes a relay, wherein the relay has a closed state allowing current flow within the conductor and an open state preventing current flow within the conductor, the method comprising:

• with a first transmitting coil disposed on an integrated circuit (IC) die within an IC package, producing a reference magnetic field at a reference frequency in response to receiving a drive current, wherein the reference magnetic field is configured to produce an induced current in the conductor when the relay is in the closed state;
• with a first coil driver disposed within the IC package, producing the drive current and providing it to the first transmitting coil;
• with magnetoresistance circuitry disposed within the IC package and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by the induced current when present, producing an output signal corresponding to the net magnetic field;
• and
• with a main signal path connected to the magnetoresistance circuitry and configured to receive the output signal, determining whether the relay is in the closed state or the open state,
• wherein the conductor is configured to conduct current having a frequency in a first frequency band, wherein producing the reference magnetic field includes producing the reference magnetic field with the reference frequency out of the first frequency band.

A method of detecting an open circuit state of a conductor using an inductive sensor, wherein the conductor includes a relay, wherein the relay has a closed state allowing current flow within the conductor and an open state preventing current flow within the conductor, the method comprising:

• with a first transmitting coil disposed on an integrated circuit (IC) die within an IC package, producing a reference magnetic field at a reference frequency in response to receiving a drive current, wherein the reference magnetic field is configured to produce an induced current in the conductor when the relay is in the closed state;
• with a first coil driver disposed within the IC package, producing the drive current and providing it to the first transmitting coil;
• with magnetoresistance circuitry disposed within the IC package and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by the induced current when present, producing an output signal corresponding to the net magnetic field;
• and
• with a main signal path connected to the magnetoresistance circuitry and configured to receive the output signal, determining whether the relay is in the closed state or the open state,
• wherein the conductor is configured to conduct current having a frequency in a first frequency band, wherein producing the reference magnetic field includes producing the reference magnetic field with the reference frequency within the first frequency band and with a spread spectrum sequence.

An inductive sensor for sensing an open-circuit state of a conductor, the sensor comprising:

• an integrated circuit (IC) disposed adjacent the conductor, the IC disposed on a die and including,
• a transmitting coil disposed within the IC and configured to produce a reference magnetic field at a reference frequency in response to receiving a drive current;
• a coil driver circuit disposed within the IC and configured to produce the drive current and provide it to the transmitting coil;
• magnetic field sensing circuitry including one or more magnetic field sensing elements disposed within the IC and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by an induced current in the conductor when present and produce an output signal corresponding to the net magnetic field;
• a main signal path connected to the magnetic field sensing circuitry configured to receive the output signal, wherein the main signal path is configured to determine, based on the out output signal, whether the conductor is in a closed or open state;
• and
• a feedback loop including a second coil and a second coil driver, wherein the feedback loop is configured to receive the output signal from the main signal path and produce a feedback magnetic field at the reference frequency, and wherein the magnetic field sensing circuitry is configured to detect the net magnetic field as a combination of the reference magnetic field, the induced magnetic field when present, and the feedback magnetic field.