Abstract: LED controllers, LED lighting systems and control methods capable of providing an average luminance intensity independent from the variation of an AC voltage. LEDs are divided into LED groups electrically connected in series between a power source and a ground. A disclosed LED controller has path switches, a management center and a line waveform sensor. Each path switch is for coupling a corresponding LED group to the ground. The management center controls the path switches. When turning off an upstream path switch, the management center controls a downstream path switch for a downstream LED group to make the driving current passing the upstream LED group substantially approach a target value. The line waveform sensor is coupled to the power source, sensing the waveform of the input voltage of the power source. The line waveform sensor is configured to decrease the target value when the input voltage increases.

Abstract: While an electronic product including passive elements is connected to an AC input voltage source, corresponding decreased currents are calculated according to a constant input/output work and a voltage curve of the input voltage source. Therefore, while the electronic product is activated under voltage sources having different scales or being unstable, the calculated decreased currents are applied so as to stabilize the input work or the output work.

Abstract: An LED driving circuit includes a current selecting circuit. The current selecting circuit controls the current transmission path in the plurality of LEDs according to respective threshold voltages of corresponding LEDs and a plurality of current limits.

Abstract: LED controllers, LED lighting systems and control methods capable of providing an average luminance intensity independent from the variation of an AC voltage. LEDs are divided into LED groups electrically connected in series between a power source and a ground. A disclosed LED controller has path switches, a management center and a line waveform sensor. Each path switch is for coupling a corresponding LED group to the ground. The management center controls the path switches. When turning off an upstream path switch, the management center controls a downstream path switch for a downstream LED group to make the driving current passing the upstream LED group substantially approach a target value. The line waveform sensor is coupled to the power source, sensing the waveform of the input voltage of the power source. The line waveform sensor is configured to decrease the target value when the input voltage increases.

Abstract: While an electronic product including passive elements is connected to an AC input voltage source, corresponding decreased currents are calculated according to a constant input/output work and a voltage curve of the input voltage source. Therefore, while the electronic product is activated under voltage sources having different scales or being unstable, the calculated decreased currents are applied so as to stabilize the input work or the output work.

Abstract: A control circuit of a driving circuit for controlling a light emitting diode (LED) light source having a plurality of areas is provided. The control circuit includes the error amplifiers receiving a feed back current signal and a external reference voltage, and generating an error signal; a buffer register receiving a serial digital signal and generating the parallel digital signals; a work register receiving the parallel digital signals and a trigger signal, and outputting the parallel digital signals when the trigger signal is at a relatively high level; and a switch module having the power switches, each of which receives the error signal and the parallel digital signal for generating a driving signal to control a driving current of a specific area of the light source, in order to control the brightness in each area of the LED light source.

Abstract: An LED driving circuit includes a current selecting circuit. The current selecting circuit controls the current transmission path in the plurality of LEDs according to respective threshold voltages of corresponding LEDs and a plurality of current limits.

Abstract: A control circuit of a driving circuit for controlling a light emitting diode (LED) light source having a plurality of areas is provided. The control circuit includes the error amplifiers receiving a feed back current signal and a external reference voltage, and generating an error signal; a buffer register receiving a serial digital signal and generating the parallel digital signals; a work register receiving the parallel digital signals and a trigger signal, and outputting the parallel digital signals when the trigger signal is at a relatively high level; and a switch module having the power switches, each of which receives the error signal and the parallel digital signal for generating a driving signal to control a driving current of a specific area of the light source, in order to control the brightness in each area of the LED light source.