Driver circuitry is coupled between a power supply and at least one LED in a solid-state lighting fixture, such that a non-isolated direct current (DC) path exists between the power supply and the at least one LED. The driver circuitry is configured to receive an AC input voltage and generate a driver output current for driving the at least one LED from the AC input voltage. By using driver circuitry that is non-isolated from the at least one LED in the solid-state lighting fixture, the efficiency of the driver circuitry may be increased, while simultaneously reducing the cost and complexity of the driver circuitry compared to conventional driver circuitry.

A LED driving device is provided, which includes a LED string including at least one LED element, at least one channel connected to the at least one LED element, a current regulator configured to regulate a current flowing through the at least one channel according to at least one corresponding control voltage, and a control signal generating circuit configured to generate a control signal based on a difference between a reference voltage and a comparative voltage. The comparative voltage is determined based on a sensing voltage, and the sensing voltage corresponds to an LED current flowing through the LED string. The control signal generating circuit is further configured to generate the at least one corresponding control voltage based on the control signal.

A resonant power converter is provided with capacitive switching mode protection. The converter produces output current and voltage according to an operating frequency, which is desirably maintained above a resonant frequency for the power converter. A controller regulates the operating frequency based on an output current relative to a reference value, which may be provided via a dimming interface. A capacitive switching mode is determinable, based on a positive relationship in a detected direction of change in an output value relative to a detected direction of change in the operating frequency. When the capacitive switching mode is determined, a preceding operating frequency is enacted and the controller disables regulation of the operating frequency therefrom. Inductive mode switching is determinable with a negative relationship between detected direction of change in the output value relative to direction of change in the operating frequency, wherein regulation of operating frequency is renewed.

A Light-Emitting Diode (LED) light system has a plurality of LED groups connected in parallel with each of the plurality of LED groups having one or more LEDs connected in series, a power circuit having a plurality of outputs with each output of the power circuit is electrically coupled to a respective one of the plurality of LED groups, and a control subsystem electrically coupled to the power circuit for individually controlling each output of the power circuit for controlling the operation of the corresponding LED group and adapting to the characteristics thereof. In some embodiments, at least one LED group may further have a switch and/or a light-angle controlling structure connected with the one or more LEDs in series and controlled by the control subsystem for selectively enabling or disabling the LED group and/or adjusting the light angle thereof.

A Light-Emitting Diode (LED) light system has a plurality of LED groups connected in parallel with each of the plurality of LED groups having one or more LEDs connected in series, a power circuit having a plurality of outputs with each output of the power circuit is electrically coupled to a respective one of the plurality of LED groups, and a control subsystem electrically coupled to the power circuit for individually controlling each output of the power circuit for controlling the operation of the corresponding LED group and adapting to the characteristics thereof. In some embodiments, at least one LED group may further have a switch and/or a light-angle controlling structure connected with the one or more LEDs in series and controlled by the control subsystem for selectively enabling or disabling the LED group and/or adjusting the light angle thereof.

Various embodiments may relate to a load driving circuit and an illumination apparatus including the same. The load driving circuit includes a Single-Ended Primary Inductor Converter (SEPIC) converter adapted to convert an input system voltage into a DC output voltage, and a BUCK converter 200 adapted to regulate a current and provide the regulated current to a load. The load driving circuit further includes a first diode and a second diode which are connected so that the SEPIC converter and the BUCK converter share one switch. According to various embodiments, it is possible to obtain constant current output characteristics and high power factor with a simple circuit structure and a low cost.

System and method for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer. For example, the system for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer includes: a first current controller configured to receive a rectified voltage generated by a rectifier that directly receives an AC input voltage without through any TRIAC dimmer; and a second current controller configured to: control a light emitting diode current flowing through one or more light emitting diodes that receive the rectified voltage not clipped by any TRIAC dimmer; and generate a sensing voltage based at least in part upon the light emitting diode current, the sensing voltage representing the light emitting diode current in magnitude.

System and method for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer. For example, the system for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer includes: a first current controller configured to receive a rectified voltage generated by a rectifier that directly receives an AC input voltage without through any TRIAC dimmer; and a second current controller configured to: control a light emitting diode current flowing through one or more light emitting diodes that receive the rectified voltage not clipped by any TRIAC dimmer; and generate a sensing voltage based at least in part upon the light emitting diode current, the sensing voltage representing the light emitting diode current in magnitude.

Devices and methods for controlling brightness of a display backlight are provided. A display backlight controller may control the brightness of the display backlight by changing a duty cycle of a PWM signal that drives the LED current. However, because of LED efficacy and response time, the final output brightness (NITS) may not be linear between 0% to 100%. The disclosed methods may be used to correct the brightness using a predetermined correction factor. Further, the minimum and maximum duty cycle of the output dimming duty cycle may be limited or corrected. In one example, a backlight controller receives an input duty cycle and determines a product of the input duty cycle and a maximum duty cycle to produce a reduced duty cycle. Moreover, the backlight driver may determine a corrected duty cycle using the correction factor. The final output duty cycle and LED current may then be determined.

An embodiment comprises: a voltage generation unit for providing a direct current signal for driving a light emitting unit; a sensing resistor; and a dimming unit which is connected between the light emitting unit and the sensing resistor and controls a current flowing in the sensing resistor and the light emitting unit, wherein the dimming unit adjusts the level of the direct current signal on the basis of a first sensing voltage as a result of sensing the voltage of a first node where a switch is connected to the light emitting unit, and a second sensing voltage as a result of sensing the voltage of a second node where the switch is connected to the sensing resistor.