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 multiple location dimming system may include a smart dimmer (e.g., a main load control device) and one or more remote dimmers (e.g., accessory devices) for controlling the amount of power delivered to a lighting load. The multiple location dimming system may be installed in place of a multiple location switch system (e.g., having three, four, or more multi-way switches), and may not require a neutral connection at any of the control devices of the multiple location dimming system. The main load control device and the accessory devices of the multiple location dimming system may be configured to display a present intensity level of a lighting load on one or more visual indicators. The accessory devices may have the same or different user interfaces as the main load control device, and may provide additional functionality over that which the main load control device offers.

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.

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.

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.

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 multiple location dimming system may include a smart dimmer (e.g., a main load control device) and one or more remote dimmers (e.g., accessory devices) for controlling the amount of power delivered to a lighting load. The multiple location dimming system may be installed in place of a multiple location switch system (e.g., having three, four, or more multi-way switches), and may not require a neutral connection at any of the control devices of the multiple location dimming system. The main load control device and the accessory devices of the multiple location dimming system may be configured to display a present intensity level of a lighting load on one or more visual indicators. The accessory devices may have the same or different user interfaces as the main load control device, and may provide additional functionality over that which the main load control device offers.

Both AC and DC Power supply systems that may be connected directly to. AC mains and are integrated on silicon are described. The AC systems include both simple on/off capabilities as well as phase control capabilities. The DC power supply may be fixed, adjustable as through a potentiometer and programmable. The power supply systems use newly invented components of AC/DC converters and bidirectional MOSFET switches.