A light emitting diode (LED) device is provided. The LED device a first LED string configured to emit light having a first color temperature; a second LED string connected to the first LED string in parallel, and configured to emit light having a second color temperature different from the first color temperature; a controller configured to generate a control signal based on a control command received from an external controller; a switching circuit configured to control brightness of any one or any combination of the first LED string and the second LED string based on the control signal; and a power supply configured to generate an internal power voltage for operation of the controller and the switching circuit.

A semiconductor device includes an oscillator configured to generate a first clock signal, a first terminal via which an input clock signal is fed in from the outside, a first counter configured to count a clock signal based on the first clock signal between edges in the input clock signal, and a controller configured to send to the oscillator an instruction to adjust the frequency of the first clock signal based on the result of comparison of the count value by the first counter with an expected value.

An LED lighting system includes switching circuity adjustably driving a string of LEDs and being controlled by a reference current and an enable signal. A controller generates the reference current and enable signal based upon a PWM signal such that the switching circuitry: sources a first LED current to the string of LEDs that is proportional to a duty cycle of the PWM signal when the duty cycle is greater than a threshold duty cycle to thereby perform analog dimming; and sources a second LED current to the string of LEDs that has a duty cycle proportional to the duty cycle of the PWM signal when the duty cycle of the PWM signal is less than the threshold duty cycle, such that an average LED current delivered to the string of LEDs is proportional to the duty cycle of the PWM signal to thereby perform digital dimming.

A dimming regulated power supply module comprising a control circuit, a voltage-stabilizing circuit, a dimming circuit, and an output port, wherein the control circuit converts city power into a supply voltage for supplying power to a LED light string through the output port, wherein the voltage-stabilizing circuit senses an internal voltage of the control circuit to generate a first voltage and a second voltage, and supplies power to a single-chip microcomputer in the dimming circuit after stabilizing the second voltage, wherein the voltage-stabilizing circuit outputs the first voltage to set the voltage range of the dimming circuit, wherein the output port transmits the dimming signal output by a dimmer to the dimming circuit, and wherein the dimming circuit generates a corresponding pulse-width modulation signal, wherein the control circuit controls the supply current according to the pulse-width modulation signal, thereby controls the brightness of the LED light string through the output port.

A dimming regulated power supply module comprising a control circuit, a voltage-stabilizing circuit, a dimming circuit, and an output port, wherein the control circuit converts city power into a supply voltage for supplying power to a LED light string through the output port, wherein the voltage-stabilizing circuit senses an internal voltage of the control circuit to generate a first voltage and a second voltage, and supplies power to a single-chip microcomputer in the dimming circuit after stabilizing the second voltage, wherein the voltage-stabilizing circuit outputs the first voltage to set the voltage range of the dimming circuit, wherein the output port transmits the dimming signal output by a dimmer to the dimming circuit, and wherein the dimming circuit generates a corresponding pulse-width modulation signal, wherein the control circuit controls the supply current according to the pulse-width modulation signal, thereby controls the brightness of the LED light string through the output port.

An apparatus includes a controller (such as associated with a power converter). The controller is operative to receive input control settings. Based on the input control settings, the controller controls a magnitude of an output current generated by the power converter. The output current from the power converter powers light emitting hardware. The controller transitions between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current.

An apparatus includes a controller (such as associated with a power converter). The controller is operative to receive input control settings. Based on the input control settings, the controller controls a magnitude of an output current generated by the power converter. The output current from the power converter powers light emitting hardware. The controller transitions between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current.

Described herein are systems and methods for operating DC-DC regulators such as LED drivers. Various embodiments herein allow a DC-DC regulator to switch between buck mode and buck-boost mode without suffering effects otherwise resulting from transient currents when switching between modes. In certain embodiments, this is accomplished by operating the DC-DC regulator in a buck-boost mode to charge a boost capacitor with a substantially constant inductor current. The inductor current is also used to control a set of switches to operate the DC-DC regulator in a buck mode to drive a load by using the capacitor as a power source.

Described herein are systems and methods for operating DC-DC regulators such as LED drivers. Various embodiments herein allow a DC-DC regulator to switch between buck mode and buck-boost mode without suffering effects otherwise resulting from transient currents when switching between modes. In certain embodiments, this is accomplished by operating the DC-DC regulator in a buck-boost mode to charge a boost capacitor with a substantially constant inductor current. The inductor current is also used to control a set of switches to operate the DC-DC regulator in a buck mode to drive a load by using the capacitor as a power source.

An illumination device and method is provided herein for controlling an LED illumination device, so that a desired luminous flux and a desired chromaticity of the device can be maintained over time as the LEDs age. According to one embodiment, the method determines an expected wavelength value and an expected intensity value for each emission LED included within the illumination device at the drive current currently applied to the emission LED and the present emitter forward voltage. In addition, the method determines a photodetector responsivity for each emission LED at the expected wavelength value and the present photodetector forward voltage. The photodetector responsivity calculated for each emission LED is used as a reference for adjusting the lumen output of the emission LED to account for LED aging affects.