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 may control the amount of power provided to an electrical load utilizing a phase control signal that operates in a reverse phase control mode, a center phase control mode, and a forward phase control mode. A load control device may be configured to determine that the electrical load should be operated via a phase control signal operating in a forward phase-control mode. After determining to operate the electrical load via the phase control signal in the forward phase-control mode, the load control device may provide the phase control signal in a reverse phase-control mode for a predetermined period of time to the electrical load, for example, to charge a bus capacitor of the electrical load. Subsequently, the load control device may be configured to switch the phase control signal to the forward phase-control mode and provide the phase control signal in the forward phase-control mode to the electrical load.

A multiple location load control system may comprise a main load control device and an accessory load control device. The main load control device may control an amount of power delivered to an electrical load from an AC power source using a control circuit and a controllably conductive device. The accessory load control device may be coupled to the main load control device via an accessory terminal. The accessory load control device may detect a user input for changing a characteristic of the electrical load and may send a signal to the main load control device indicating the user input. The main load control device may detect a pattern of the signal based on a threshold and further determine the user input in response to the detected pattern. The main load control device may adjust the threshold based on line/load conditions of the multiple location load control system.

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 generally comprises creating a signal conditioner that is capable of filtering, converting, segmenting and producing a periodic waveform from an electrical source, converting in into an electrical signal to drive an electrical device, such as a LED lamp, so that the behavior of the device driven by the electrical signal enables the device to perform a function that is practically free of the variations present in the main electrical source.

An LED lighting apparatus is configured to light in response to an input power signal. The LED lighting apparatus includes a power supply module, configured to receive the input power signal in order to generate a driving power signal, and an LED module configured to light in response to the driving power signal. The power supply module comprises a demodulating circuit configured to receive the input power signal and demodulate the received input power signal, in order to generate a dimming control signal for controlling luminance of the LED module, wherein the demodulating circuit demodulates the input power signal based on a phase-cut angle of the input power signal.

A multiple location load control system may comprise a main load control device and an accessory load control device. The main load control device may control an amount of power delivered to an electrical load from an AC power source using a control circuit and a controllably conductive device. The accessory load control device may be coupled to the main load control device via an accessory terminal. The accessory load control device may detect a user input for changing a characteristic of the electrical load and may send a signal to the main load control device indicating the user input. The main load control device may detect a pattern of the signal based on a threshold and further determine the user input in response to the detected pattern. The main load control device may adjust the threshold based on line/load conditions of the multiple location load control system.

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 zero-crossing detection method, and devices incorporating the method, enable a selectively enabled bias to pull-up a zero-crossing signal, thereby enabling monitoring of the zero-crossing of both half-cycles of the alternating current (AC). This improves synchronization of the device in noisy environments and enables the detection of dimming problems during either half-cycle. Aspects can detect improper dimmer firing events on either polarity of the power cycle and restore normal dimmer operations when needed.

A multiple location load control system may comprise a main load control device and an accessory load control device. The main load control device may control an amount of power delivered to an electrical load from an AC power source using a control circuit and a controllably conductive device. The accessory load control device may be coupled to the main load control device via an accessory terminal. The accessory load control device may detect a user input for changing a characteristic of the electrical load and may send a signal to the main load control device indicating the user input. The main load control device may detect a pattern of the signal based on a threshold and further determine the user input in response to the detected pattern. The main load control device may adjust the threshold based on line/load conditions of the multiple location load control system.