In a load control system as described, each of a plurality of switch circuits includes a switch electrically connected between an associated one second terminal out of a plurality of second terminals and a first terminal. A control circuit controls the switch that each of the plurality of switch circuits includes and thereby controls supply of power to a load associated with each of the plurality of switch circuits. A power supply circuit is electrically connected between the plurality of second terminals and the first terminal and receives power from a power supply via the first terminal and at least one second terminal out of the plurality of second terminals and thereby generates power to be supplied to at least the control circuit.

In a load control system as described, each of a plurality of switch circuits includes a switch electrically connected between an associated one second terminal out of a plurality of second terminals and a first terminal. A control circuit controls the switch that each of the plurality of switch circuits includes and thereby controls supply of power to a load associated with each of the plurality of switch circuits. A power supply circuit is electrically connected between the plurality of second terminals and the first terminal and receives power from a power supply via the first terminal and at least one second terminal out of the plurality of second terminals and thereby generates power to be supplied to at least the control 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.

System and method for controlling one or more light emitting diodes. For example, the system includes a bleeder configured to receive a rectified voltage generated by a rectifying bridge, and a dimmer detector configured to receive an input voltage generated by a voltage divider, determine whether or not the rectified voltage is associated with a TRIAC dimmer, and output a control signal to the bleeder. The voltage divider is configured to receive the rectified voltage, and the input voltage indicates a magnitude of the rectified voltage.

Disclosed is a phase-cut dimmer, comprising an AC switch coupled in series between an AC supply and a load; a DC power supply powered from a voltage across the switch; a zero-crossing detector of a phase-cut AC voltage across the switch; a timer generating a timing signal of a duty-cycle proportional to a variable fraction of a peak voltage of a sawtooth signal, wherein the sawtooth signal is synchronized to the zero-crossing detector; a blanking signal generator triggered by a duty-cycle detector to reduce the duty-cycle when the duty-cycle of the timing signal exceeds a predetermined maximum limit; and an operation mode selector activated by an output of an inductive load detector.

Disclosed is a phase-cut dimmer, comprising an AC switch coupled in series between an AC supply and a load; a DC power supply powered from a voltage across the switch; a zero-crossing detector of a phase-cut AC voltage across the switch; a timer generating a timing signal of a duty-cycle proportional to a variable fraction of a peak voltage of a sawtooth signal, wherein the sawtooth signal is synchronized to the zero-crossing detector; a blanking signal generator triggered by a duty-cycle detector to reduce the duty-cycle when the duty-cycle of the timing signal exceeds a predetermined maximum limit; and an operation mode selector activated by an output of an inductive load detector.

A 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 (such as, a triac) coupled between the source and the load, a gate coupling circuit arranged to conduct current through a gate terminal of the thyristor, and a control circuit configured to control the gate coupling circuit. The control circuit may control the gate coupling circuit to conduct a pulse of current through the gate terminal to render the thyristor conductive at a firing time during a present half cycle of the AC power source, and allow the gate coupling circuit to conduct at least one other pulse of current after the firing time during the present half cycle.

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 modular dimmer assembly, including a communications circuit configured to send and receive wireless communication, a control circuit configured to receive an AC input at a first pulse width and adjust the brightness of at least one lighting device, in response to the communications circuit receiving a signal, by producing an AC output at a second pulse width, a regulation circuit, controlled by the AC output, including a flyback switch mode power supply (SMPS) and a capacitor, wherein the flyback SMPS charges the capacitor and the control circuit monitors a voltage of the capacitor to determine the second pulse width, and wherein the modular dimmer assembly is a two-wire device.

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.