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.

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.

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 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.

A detection circuit configured to detect the presence of a TRIAC dimmer for an LED driver, can include: a sampling circuit configured to receive a DC bus voltage, and to generate a voltage sampling signal that characterizes the DC bus voltage; and a detector configured to determine whether the LED driver is provided with the TRIAC dimmer in accordance with a duration of the voltage sampling signal being continuously greater than a first reference voltage.

A detection circuit configured to detect the presence of a TRIAC dimmer for an LED driver, can include: a sampling circuit configured to receive a DC bus voltage, and to generate a voltage sampling signal that characterizes the DC bus voltage; and a detector configured to determine whether the LED driver is provided with the TRIAC dimmer in accordance with a duration of the voltage sampling signal being continuously greater than a first reference voltage.

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.

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.

An apparatus can include: a light-emitting diode (LED) drive circuit having a silicon-controlled rectifier dimmer; and a bus voltage adjustment circuit configured to adjust a direct current bus voltage to delay a turn-on time instant of the silicon-controlled rectifier dimmer when a conduction angle signal is greater than an angle threshold.

An apparatus can include: a light-emitting diode (LED) drive circuit having a silicon-controlled rectifier dimmer; and a bus voltage adjustment circuit configured to adjust a direct current bus voltage to delay a turn-on time instant of the silicon-controlled rectifier dimmer when a conduction angle signal is greater than an angle threshold.