A controller protection circuit for a voltage power optimiser. The circuit having: a first terminal for connecting to a first end of a winding in the voltage power optimiser; a second terminal for connecting to a second end of the winding in the voltage power optimiser; and a thyristor. The controller protection circuit also includes a thyristor gate control circuit. The thyristor gate control circuit is configured to: set the gate control signal such that the thyristor is configured to conduct in response to a potential difference between the anode terminal and the cathode terminal of the thyristor; and set the gate control signal such that the thyristor is configured not to conduct in response to a signal received from a voltage controller. The thyristor gate control circuit includes a normally-on switch having a conduction channel and a control terminal, and a photovoltaic isolator configured to set the gate control signal such that the thyristor is configured not to conduct in response to a signal received from a voltage controller.

A power converter circuit includes a power stage that includes a transformer and a switch. The switch can be controlled in response to a PWM signal to provide a primary current through a primary winding of the transformer to induce a secondary current in a secondary winding of the transformer to generate an output voltage. The power stage includes a switching node between the switch and the primary winding having a switching voltage. The circuit also includes a switching controller configured to generate the PWM signal in response to a ramp signal. The ramp signal can have an amplitude of a slope that is proportional to a decay rate of a magnetizing current of the transformer and generated in response to feedback from the power stage. The switch can be activated in response to the switching voltage having an amplitude of approximately zero volts based on the amplitude of the ramp signal.

Disclosed is a method for triggering the switching of a switching transistor of a quasi-resonant DC-to-DC voltage converter to the on state. The method includes the steps of phase-shifting the drain voltage of the transistor by a predetermined temporal phase-shift value that corresponds to the difference between the duration of a quarter of the period of the damped sinusoidal oscillation generated when the transistor is switched off and the period of time that elapses between the command to switch the transistor to the on state and the transistor actually conducting, and, when the phase-shifted voltage is equal to the reference voltage, triggering the command to switch the transistor to the on state such that the transistor starts conducting at the time when the value of the drain voltage is at a minimum.

In some embodiments of the present disclosure, a method for operating an inductor coil may include: charging a capacitor by means of a charging current at a reference voltage; and discharging the charged capacitor in an oscillating manner via the inductor coil. The discharging is ended when a current passing through the inductor coil has passed through an entire oscillation period or a multiple thereof.

A circuit and a method for detecting a current zero-crossing point, and a circuit and method for detecting a load voltage are disclosed. The circuit for detecting current zero-crossing point includes: a load power supply circuit (14), a voltage-dividing resistor (16), a transistor switch (15), a zero-crossing detection circuit (19); the load power supply circuit (14) includes: a load (11), a diode (13), and an inductor (12); one end of the load power supply circuit (14) is connected with the operating voltage input terminal, the other end of the load power supply circuit (14) is connected with a first end of the transistor switch (15) and a first end of the voltage-dividing resistor (16), a second end of the voltage-dividing resistor (16) and a second end of the transistor switch (15) are connected with the ground, the load voltage is controlled by the transistor switch (15), the voltage-dividing terminal of the voltage-dividing resistor (16) is connected to a signal input terminal of the zero-crossing detection circuit (19), the zero-crossing detection circuit (19) is used to determine whether the current of the diode (13) crosses zero to obtain the on time of the diode (13), and the circuit for detecting load voltage uses the on time of the diode (13) and the on time of the transistor switch (15) to obtain the load voltage. The circuits are simple, but with high detection efficiency and low cost.

Disclosed examples provide DC-DC converters and control circuits to provide high and low-side driver signals and to selectively adjust a delay time between a low-side switching device turning off and a high-side switching device turning on according to a comparator signal, including a clocked comparator circuit referenced to a switching node to sample the voltage across the high-side switching device in response to a first edge of the high-side driver signal, and to generate the comparator signal indicating a polarity of the sampled high-side switch voltage to facilitate zero voltage switching of the high-side switching device.

A microcontroller based multifunctional electronic switch using a detection circuit design to convert external motion signals into message carrying sensing signals readable to the microcontroller. Based on the time length of sensing signals and the format of the sensing signals received in a preset instant period of time the microcontroller through the operation of its software program codes written in the OTPROM is able to recognize the working modes chosen by the external signal generating user and thereby selecting the appropriate loops of subroutine for execution. The system and method of the present invention may simultaneously be applicable to detection circuit design using infrared ray sensor, electrostatic induction sensor, conduction based touch sensor or push button sensor for performing multifunction such as controlling the on/off switch performance, the diming or speed control and the delay timer management within the capacity of a single lighting device or an electrical appliance.

A compact solid state relay (7) is provided. Solid state devices (74, 75), such as Triacs or Thyristors are used to implement the relay functionality. The device is at least partially enclosed in a housing that has pins for mounting on an electronics board. A number of “U” shaped jumpers (72) or other jumpers or wires are provided in the housing to act as heat sinks. A subminiature fan (70) is positioned to create an air flow over the heat sinks and dissipate heat from the device.

A switch-mode DC converter configured to generate a converted voltage from an input voltage is provided. The switch-mode DC converter includes an inductor configured to store energy, and a switch coupled with the inductor at a switching node, wherein the switch is configurable to be turned on or off to control the discharging of the energy stored at the inductor to an output node of the converter, wherein the output node is configured to provide the converted voltage. The switch-mode DC converter also includes a circuit configured to control a timing of turning-off of the switch based on a voltage difference between the switch, wherein a measurement of the voltage difference is adjusted based on a voltage at the switching node.

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.