System and method for controlling one or more light emitting diodes. For example, the system for controlling one or more light emitting diodes includes a current generator configured to generate a first current flowing through one or more light emitting diodes. The one or more light emitting diodes are configured to receive a rectified voltage generated by a rectifying bridge coupled to a TRIAC dimmer. Additionally, the system includes a bleeder configured to receive the rectified voltage, and a controller configured to receive a sensing voltage from the current generator and output a control signal to the bleeder. The sensing voltage indicates a magnitude of the first current.

System and method for controlling one or more light emitting diodes. For example, the system includes: a voltage detector configured to receive a rectified voltage associated with a TRIAC dimmer and generated by a rectifying bridge and generate a first sensing signal representing the rectified voltage; a distortion detector configured to receive the first sensing signal, determine whether the rectified voltage is distorted or not based at least in part on the first sensing signal, and generate a distortion detection signal indicating whether the rectified voltage is distorted or not; and a phase detector configured to receive the first sensing signal and generate a phase detection signal indicating a detected phase range within which the TRIAC dimmer is in a conduction state based at least in part on the first sensing signal.

Apparatus and methods for controlling correlated color temperature (CCT) and lighting intensity in lighting fixtures are described. The CCT and intensity may be controlled independently over conventional AC wiring using a conventional dimmer. A lighting controller that resembles a conventional dimmer and that can be installed in place of a dimmer may be used instead of a conventional dimmer to access more control functionalities, still using conventional AC wiring. Wireless communication with the lighting fixture and/or lighting controller are possible.

A dummy load for automotive LED lights is revealed. The dummy load includes an automotive battery and a control module which is electrically connected both a body computer and a LED light module and provided with a LED control circuit and a charge control circuit. The charge control circuit includes a signal mixer circuit receiving signals from the body computer and discharge signals of the automotive battery, a charger integrated circuit (IC) and a feedback control circuit for battery both electrically connected to the signal mixer circuit, and a battery charging circuit electrically connected to the charger IC and transmitting charge signals to the feedback control circuit for battery and the automotive battery. Thereby a conventional dummy load resistor is replaced by the automotive battery for protecting the automotive LED light from overheating, increasing product stability and recycling a part of electricity for recharge of the automotive battery.

A dummy load for automotive LED lights is revealed. The dummy load includes an automotive battery and a control module which is electrically connected both a body computer and a LED light module and provided with a LED control circuit and a charge control circuit. The charge control circuit includes a signal mixer circuit receiving signals from the body computer and discharge signals of the automotive battery, a charger integrated circuit (IC) and a feedback control circuit for battery both electrically connected to the signal mixer circuit, and a battery charging circuit electrically connected to the charger IC and transmitting charge signals to the feedback control circuit for battery and the automotive battery. Thereby a conventional dummy load resistor is replaced by the automotive battery for protecting the automotive LED light from overheating, increasing product stability and recycling a part of electricity for recharge of the automotive battery.

A load control device for controlling power delivered from an AC power source to an electrical load may comprise a thyristor, a gate current path, and a control circuit. The control circuit may be configured to control the gate current path to conduct a pulse of gate current through a gate terminal of the thyristor to render the thyristor conductive at a firing time during a half-cycle of the AC power source. The control circuit may operate in a first gate drive mode in which the control circuit renders the gate current path non-conductive after a pulse time period from the firing time. The control circuit may operate in a second gate drive mode in which the control circuit maintains the gate current path conductive after the pulse time period during the half-cycle.

A load control device for controlling power delivered from an AC power source to an electrical load may comprise a thyristor, a gate current path, and a control circuit. The control circuit may be configured to control the gate current path to conduct a pulse of gate current through a gate terminal of the thyristor to render the thyristor conductive at a firing time during a half-cycle of the AC power source. The control circuit may operate in a first gate drive mode in which the control circuit renders the gate current path non-conductive after a pulse time period from the firing time. The control circuit may operate in a second gate drive mode in which the control circuit maintains the gate current path conductive after the pulse time period during the half-cycle.

An apparatus for an LED driver with a silicon-controlled dimmer, can include: a bleeder circuit coupled to a DC bus of the LED driver; and a controller configured to control the bleeder circuit to draw a bleeder current from the DC bus when a conduction angle of the silicon-controlled dimmer is less than an angle threshold, in order to maintain a conduction state of the silicon-controlled dimmer.

An apparatus for an LED driver with a silicon-controlled dimmer, can include: a bleeder circuit coupled to a DC bus of the LED driver; and a controller configured to control the bleeder circuit to draw a bleeder current from the DC bus when a conduction angle of the silicon-controlled dimmer is less than an angle threshold, in order to maintain a conduction state of the silicon-controlled dimmer.

Embodiments of the present application disclose an adaptive bleeder control method and circuit, the method including: acquiring a peak characterizing voltage of a grid, wherein the peak characterizing voltage is a voltage value that characterizes a peak state among the grid characterizing voltages that are detected within a preset time and being scaled in proportion to the magnitude of the grid voltage; generating a switch control signal according to the peak characterizing voltage; performing switch control according to the switch control signal to generate a bleeder signal; and performing bleeder control on a light source device according to the bleeder signal to connect or disconnect a loop with a SCR in the light source device. In the present application, the dimming function of the light source device while preventing the bleeder current path from being constantly closed and reducing system efficiency may be implemented.