The present disclosure concerns a method and a circuit for controlling first and second switches electrically in series, wherein one or a plurality of crossings of a voltage threshold by a voltage across the first switch cause a conductive state of the second switch.

Methods, systems, and devices for controlling a variable capacitor. One aspect features a variable capacitance device that includes a capacitor, a first transistor, a second transistor, and control circuitry. The control circuitry is configured to adjust an effective capacitance of the capacitor by performing operations including detecting a zero-crossing of an input current at a first time. Switching off the first transistor. Estimating a first delay period for switching the first transistor on when a voltage across the capacitor is zero. Switching on the first transistor after the first delay period from the first time. Detecting a zero-crossing of the input current at a second time. Switching off the second transistor. Estimating a second delay period for switching the second transistor on when a voltage across the capacitor is zero. Switching on the second transistor after the second delay period from the second time.

The present disclosure provides a nitride-based bidirectional switching device with substrate potential management capability. The device has a control node, a first power/load node, a second power/load node and a main substrate, and comprises: a nitride-based bilateral transistor and a substrate potential management circuit configured for managing a potential of the main substrate. By implementing the substrate potential management circuit, the substrate potential can be stabilized to a lower one of the potentials of the first source/drain and the second source/drain of the bilateral transistor no matter in which directions the bidirectional switching device is operated. Therefore, the bilateral transistor can be operated with a stable substrate potential for conducting current in both directions.

A relay circuit, including a solid state relay switch, connected to a first relay line and to a charging capacitor, and connected to a second relay line. The relay circuit may also include a solid state relay control circuit, coupled between the charging capacitor and the solid state relay switch. The solid state relay control circuit may include a voltage detection circuit, having an input coupled to an output of the charging capacitor, and having an output arranged to generate a LOW voltage signal when a voltage level of the charging capacitor is below a low threshold value. The solid state relay control circuit may also include a zero crossing circuit, coupled to the first relay line and the second relay line, and having an output to generate a clock signal when a zero crossing event takes place between the first relay line and the second relay line.

A relay circuit may include a solid state relay switch, coupled to an external voltage line and to an charging capacitor; and a solid state relay control circuit, coupled between the charging capacitor and the solid state relay switch. The solid state relay control circuit may be arranged to: turn the solid state relay switch to an OFF state when a capacitor voltage of the charging capacitor falls below a low threshold value; and change the solid state relay switch from the OFF state to an ON state when the capacitor voltage increases above a high threshold value.

A method for actuating a semiconductor power switch of an AC circuit is provided, which can be activated or deactivated by the semiconductor power switch. The method has the following steps: a) ascertaining the present current value and the present voltage value of the AC circuit; b) ascertaining whether the present current value exceeds a specifiable maximum value and if so, c1) generating an actuation signal for deactivating the current circuit, c2) generating an actuation signal for activating the current circuit within a period of time after generating the actuation signal for deactivating the current circuit, wherein the period of time is less than or equal to the period duration of the voltage, and c3) ascertaining whether the present current value exceeds a specifiable maximum value, which corresponds to the previous maximum value or is less than the previous maximum value, after activating the current circuit.

A load switch and a power system are provided. The load switch includes a power input terminal, a power output terminal, a voltage-current conversion circuit, a capacitor and a comparator. The power input terminal is configured to receive an input voltage. The power output terminal is configured to provide an output voltage. The voltage-current conversion circuit includes a first input terminal, a second input terminal and a current difference output terminal. The first input terminal and the second input terminal are connected to the power output terminal and the power input terminal, respectively, and configured to receive the output voltage and the input voltage, respectively. A current difference characterizing a voltage difference between the output voltage and the input voltage is output at the current difference output terminal.

A bidirectional bipolar transistor switch arrangement, including: a first bipolar transistor and a second bipolar transistor connected in anti-parallel between a first terminal and a second terminal, a resistor connected to the base of the first bipolar transistor and the second bipolar transistor and to a control terminal, a first diode connected with anode to the first terminal, and a second diode connected with anode to the second terminal, the first diode and the second diode being connected via respective cathodes to a supply terminal. The bidirectional bipolar transistor switch arrangement is able to control the power supply within a daisy chain with low drop voltage.

The present disclosure provides a nitride-based bidirectional switching device with substrate potential management capability. The device has a control node, a first power/load node, a second power/load node and a main substrate, and comprises: a nitride-based bilateral transistor and a substrate potential management circuit configured for managing a potential of the main substrate. By implementing the substrate potential management circuit, the substrate potential can be stabilized to a lower one of the potentials of the first source/drain and the second source/drain of the bilateral transistor no matter in which directions the bidirectional switching device is operated. Therefore, the bilateral transistor can be operated with a stable substrate potential for conducting current in both directions.

The present disclosure provides a nitride-based bidirectional switching device with substrate potential management capability. The device has a control node, a first power/load node, a second power/load node and a main substrate, and comprises: a nitride-based bilateral transistor and a substrate potential management circuit configured for managing a potential of the main substrate. By implementing the substrate potential management circuit, the substrate potential can be stabilized to a lower one of the potentials of the first source/drain and the second source/drain of the bilateral transistor no matter in which directions the bidirectional switching device is operated. Therefore, the bilateral transistor can be operated with a stable substrate potential for conducting current in both directions.