Apparatus and methods for transient overstress protection with false condition shutdown are provided herein. In certain configurations, a high-voltage tolerant actively-controlled protection circuit includes a transient overstress detection circuit, a clamp circuit electrically connected between a first node and a second node, a bias circuit that biases the clamp circuit, and a false condition shutdown circuit. The transient overstress detection circuit generates a detection signal indicating whether or not a transient overstress event is detected between the first and second nodes. Additionally, the false condition shutdown circuit generates a false condition shutdown signal based on low pass filtering a voltage difference between the first and second nodes, thereby determining independently whether or not power is present. The bias circuit controls operation of the clamp circuit in an on state or an off state based on the detection signal and the false condition shutdown signal.

A control device includes a triac and a first diode that is series-connected between the triac and a first terminal of the device that is configured to be connected to a cathode gate of a thyristor. A second terminal of the control device is configured to be connected to an anode of the thyristor. The triac has a gate connected to a third terminal of the device that is configured to receive a control signal. The thyristor is a component part of one or more of a rectifying bridge circuit, an in-rush current limiting circuit or a solid-state relay circuit.

A control device includes a triac and a first diode that is series-connected between the triac and a first terminal of the device that is configured to be connected to a cathode gate of a thyristor. A second terminal of the control device is configured to be connected to an anode of the thyristor. The triac has a gate connected to a third terminal of the device that is configured to receive a control signal. The thyristor is a component part of one or more of a rectifying bridge circuit, an in-rush current limiting circuit or a solid-state relay circuit.

A control device includes a triac and a first diode that is series-connected between the triac and a first terminal of the device that is configured to be connected to a cathode gate of a thyristor. A second terminal of the control device is configured to be connected to an anode of the thyristor. The triac has a gate connected to a third terminal of the device that is configured to receive a control signal. The thyristor is a component part of one or more of a rectifying bridge circuit, an in-rush current limiting circuit or a solid-state relay circuit.

Apparatus and methods for transient overstress protection with false condition shutdown are provided herein. In certain configurations, a high-voltage tolerant actively-controlled protection circuit includes a transient overstress detection circuit, a clamp circuit electrically connected between a first node and a second node, a bias circuit that biases the clamp circuit, and a false condition shutdown circuit. The transient overstress detection circuit generates a detection signal indicating whether or not a transient overstress event is detected between the first and second nodes. Additionally, the false condition shutdown circuit generates a false condition shutdown signal based on low pass filtering a voltage difference between the first and second nodes, thereby determining independently whether or not power is present. The bias circuit controls operation of the clamp circuit in an on state or an off state based on the detection signal and the false condition shutdown signal.

A switching device (28) comprising a primary switching block (30) including at least one semiconductor switch (34); and a switching control unit (32) to control the switching of the or each semiconductor switch (34). The switching device further includes a crowbar circuit (46) comprising a crowbar switch (56) switchable to selectively allow current to flow through the crowbar switch (56) in order to bypass the or each switching module; and a secondary switching block including a switching element (58) connected across a control electrode and a cathode of the crowbar switch (56). The switching element (58) is in communication with the switching control unit (32) to receive, in use, a control signal (66) generated by the switching control unit (32) when the primary switching block (30) is operating within predefined operating parameters.

A control device includes a triac and a first diode that is series-connected between the triac and a first terminal of the device that is configured to be connected to a cathode gate of a thyristor. A second terminal of the control device is configured to be connected to an anode of the thyristor. The triac has a gate connected to a third terminal of the device that is configured to receive a control signal. The thyristor is a component part of one or more of a rectifying bridge circuit, an in-rush current limiting circuit or a solid-state relay circuit.

A rectifying bridge includes a bypass circuit with a resistor and a thyristor connected in parallel between a second internal node and a second output node. The bypass circuit limits inrush current during charging of a capacitor connected between the first and second output nodes and switches the thyristor to an on state after the capacitor reaches a predetermined charge level to prevent overheating of the resistor. The rectifying bridge further includes first and second branches connected in parallel between a first internal node and the second internal node, each branch including a pair of diodes configured to rectify an input AC voltage. A control device, having a triac and a diode series-connected between the triac and the thyristor, delivers a control signal to the thyristor to enable switching. The control device operates independently of input voltage polarity and can be implemented as part of an integrated circuit.

We describe a smart high voltage/power III-nitride semiconductor based diode or rectifier comprising first and second terminals, and further comprising an active device (e.g. a transistor such as a GaN HEMT transistor), a sensing device (e.g. a sensing diode/transistor), a sensing load (e.g. a resistor), wherein the smart high voltage/power III-nitride semiconductor based diode or rectifier is configured to output a sensing signal corresponding a current through the sensing device and/or a voltage drop across the sensing load, wherein the sensing signal is indicative of a current flowing between the first and second terminal when a bias is applied between the first and second terminals.