A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

A load control device coupled between an AC power source and an electrical load may operate in a three-wire mode or a two-wire mode based on whether the load control device is connected to a neutral side of the AC power source. The load control device may further comprise first and second zero-cross detect circuits to be respectively used in the two-wire mode or the three-wire mode, and a neutral wire detect circuit configured to generate a neutral-wire detect signal indicating whether the load control device is connected to the neutral side of the AC power source. A control circuit of the load control device may determine whether the load control device should operate in the two-wire mode or in the three-wire mode in response to the neutral-wire detect signal.

A leakage protection circuit and a dimming drive circuit are provided. A leakage detection circuit is configured to detect whether leakage occurs between two input terminals that receive an external signal. When leakage occurs, leakage protection measures are taken. A pulse generation circuit receives the sampling signal characterizing the voltage between the two input terminals to compare the sampling signal with two thresholds to control a detection path of the leakage detection circuit to be turned on or off according to a comparison result. The leakage detection path is enabled to be turned on twice by setting two pulse signals in a power frequency period, which can consider the leakage detection of the front-edge phase-cutting dimming and rear-edge phase-cutting dimming of the dimming drive circuit and has a wide range of applications.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

The invention discloses a method for controlling a bleeder connected to a phase-cut dimmer and a circuit connected to a phase-cut dimmer. The method includes detecting an input voltage of the bleeder to obtain a detection voltage, and comparing the detection voltage and a preset reference voltage, wherein during a first time period, the detection voltage is less than the preset reference voltage, a start point of the first time period is a first moment, and an end point of the first time period is a second moment; delaying a first preset duration on the basis of the second moment to turn off the bleeder; and advancing a second preset duration on the basis of the first moment to turn on the bleeder.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit comprising two MOS-gated transistors, and a control circuit. The control circuit generates first and second drive voltages for individually controlling the MOS-gated transistors, and controls the gate coupling circuit to cause the MOS-gated transistors to conduct a pulse of current through a gate terminal of the thyristor to render the thyristor conductive at a firing time during a present half cycle of the AC power source, and to allow the MOS-gated transistors to conduct at least one other pulse of current through the gate terminal after the firing time during the present half cycle.

A method of dimming an LED luminaire and a dimmable LED luminaire includes two pluralities of LEDs. The first plurality emits electromagnetic radiation at a first frequency to react with a remote phosphor and provide a phosphor illumination. The second plurality of LEDs are phosphor LEDs that emit phosphor electromagnetic radiation at a second frequency to react with the remote phosphor and provide double-phosphor illumination. The phosphors and LEDs are configured to produce specific color points when the LEDs are at full power and at full dim. When the luminaire receives a dimming signal, the first plurality of LEDs dim the phosphor illumination over a majority of the luminaire's illumination range, but the second plurality of LEDs continue to receive constant current and provide undimmed double-phosphor illumination over the majority of the luminaire's illumination range.

The present invention relates to a driver device (60) for driving a load (12), in particular an LED unit comprising one or more LEDs, said driver device comprising input terminals (28, 30) for receiving an input voltage (V12) from an external power supply (16), output terminals for providing an output voltage to the load (12) for driving the load (12), a converter unit (34) for converting the input voltage (VI 2) to a converted voltage (VI 4) and for providing the converted voltage (VI 4) to internal connection elements (63, 64) of the driver device (60), a signal control device (62) for applying an electrical signal (I) to at least one of the connection elements (63, 64), and a detection circuit for detecting a phase angle of the input voltage (VI 2) by measuring a voltage drop of the converted voltage (VI 4) caused by the electrical signal (I).

A trailing edge phase control dimmer circuit for controlling alternating current (AC) power to a load, the circuit including: a switching circuit for controlling delivery of AC power to the load by conducting power to the load in an ON state and not conducting power to the load in an OFF state; and a switching control circuit for controlling turn-OFF and turn-ON of the switching circuit at each cycle of the AC to control switching of the ON and OFF states of the switching circuit, wherein the switching control circuit controlling turn-OFF of the switching circuit includes controlling a turn-OFF transition of the switching circuit between the ON state and the OFF state of the switching circuit extending for a selected turn-OFF transition time, and wherein the switching control circuit further includes a dv/dt feedback circuit for controlling a turn-OFF transition profile indicative of a drain voltage of the switching circuit of the turn-OFF transition and the selected turn-OFF transition time by returning at least some dv/dt feedback current generated by the switching circuit back to the switching circuit, whereby the dv/dt feedback circuit is configured to control said at least some dv/dt feedback current over the turn-OFF transition so as to reduce a rate of change of at least an initial region of the turn-OFF transition profile to minimise harmonics generation by the switching circuit.

System and method for controlling one or more light emitting diodes. For example, the system includes: a phase detector configured to process information associated with a rectified voltage generated by a rectifier and related to a TRIAC dimmer, the rectified voltage corresponding to a first waveform during a first half cycle of an AC voltage and corresponding to a second waveform during a second half cycle of the AC voltage, the phase detector being further configured to generate a phase detection signal representing a first time duration during which the first waveform indicates that the rectified voltage is larger than a predetermined threshold and representing a second time duration during which the second waveform indicates that the rectified voltage is larger than the predetermined threshold; and a mode detector configured to process information associated with the rectified voltage.