Abstract: A single-stage AC-DC power converter for powering a load at a substantially constant current, and related methods and systems. The AC-DC power converter includes a high power factor correction (PFC) circuit configured in a flyback topology and operating in transition mode. The flyback PFC circuit has a PFC controller and is configured to draw an input AC current from an AC power supply. The input AC current has a first total harmonic distortion (THD). The flyback PFC circuit outputs a DC current to the load. The PFC controller is configured to sense a rectified input voltage. By multiplying the rectified input voltage sensed by the PFC controller, the input AC current drawn by the flyback PFC circuit has a second, much improved THD, which is achievable without the need of an expensive PFC controller. The rectified input voltage sensed by the PFC controller is multiplied using a Zener diode ladder.

Abstract: A solid light source lighting device includes: a step-down chopper circuit including a switching element and outputting a DC power by turning on and off the switching element; a capacitor connected in parallel to a solid light source connected across output terminals of the step-down chopper circuit; and a control circuit determining a control value for a switching operation of the switching element based on a dimming signal for indicating a dimming ratio of the solid light source, and performing switching control of the switching element based on the control value. When performing switching control of the switching element so that the dimming ratio becomes high based on the dimming signal indicating a first dimming ratio, the control circuit performs the switching control of the switching element based on the control value that becomes a second dimming ratio higher than the first dimming ratio for a prescribed time period.

Abstract: A power control/lighting system includes a controller to provide compatibility between a lamp ballast configured to receive a dedicated dimmer signal and a phase control dimmer. In at least one embodiment, the controller converts a phase control dimming signal into dimming information useable by a lamp ballast of a gas discharge lamp based lighting system. Additionally, in at least one embodiment, the controller also controls power factor correction of the power control/lighting system. In at least one embodiment, the controller provides dimming information based on the phase control dimming signal that allows the lamp ballast to be used in conjunction with a phase control dimmer.

Abstract: In at least one embodiment, an electronic system includes a controller, and the controller provides compatibility between an electronic light source and a trailing edge dimmer. In at least one embodiment, the controller is capable of predicting an estimated occurrence of a trailing edge of a phase cut AC voltage and accelerating a transition of the phase cut AC voltage from the trailing edge to a predetermined voltage threshold. In at least one embodiment, the controller predicts an estimated occurrence of the trailing edge of the phase cut AC voltage on the basis of actual observations from one or more previous cycles of the phase cut AC voltage.

Abstract: A load driving device includes a switch element configured to generate an output voltage to a load from an input voltage depending on an ON/OFF operation thereof, a switch controller configured to control the ON/OFF operation of the switch element such that a feedback voltage obtained by subtracting a dropped voltage of the load from the output voltage and a predetermined reference voltage are maintained to be consistent, and a variable current source configured to perform ON/OFF controlling of a driving current flowing to the load in response to a driving current control signal. When the switch element is in an ON state at an OFF timing of the driving current, the switch controller maintains the switch element in the ON state thereafter, and turns off the switch element when the ON period of the switch element reaches a predetermined period.

Abstract: A display apparatus is provided. The display apparatus includes a display panel which displays an image, a LED module which provides backlight to the display panel, a LED driving unit which selectively uses current of an inductor to apply driving voltage to the LED module, a sensing unit which senses a current value of the inductor, and a switching control unit which adjusts the driving voltage according to sensing result by the sensing unit.

Abstract: An LED driver for controlling a current supplied to an LED fixture, the LED driver including a switched mode power supply (SMPS) for providing the current to the LED array and a control unit for controlling a switch of the SMPS. The control unit includes an input terminal connected to a current sensing circuit and the switch is connected to the LED fixture at a node downstream of the LED fixture. The current sensing circuit of the LED driver provides a feedback signal to the input terminal of the control unit; the current sensing circuit including a current sensor arranged to provide, when the switch is closed, the feedback signal representing a level of the current supplied to the LED fixture; the current sensing circuit further providing the feedback signal indicating a zero-crossing of the current supplied to the LED fixture when the switch is open.

Abstract: A method for driving an LED connected to a power switch is provided. The method includes: determining a duty cycle of a pulse sequence for controlling the power switch according to a present current and a predetermined operating current of the LED; generating the pulse sequence according to the duty cycle and according to at least one of a randomized period sequence and a randomized pulse position sequence; and controlling switching operation of the power switch by the pulse sequence, so as to drive the LED. An apparatus for driving a light emitting diode, an apparatus for dimming a light emitting diode and illumination systems are also provided.

Abstract: A filament preheat module for preheating a filament of a lamp powered by a power circuit including an inverter, the inverter comprising an inductively coupled conductor, an inductively coupled conductor of the filament preheat module magnetically coupled to the inductively coupled conductor of the inverter to power the filament during preheating, and a switching circuit configured to electrically connect the power from the inductively coupled conductor of the filament preheat module to the filament. The switching module is configured to cutoff the power to the filament from the filament preheat module after a predetermined time period during preheating.

Abstract: A process instrument includes a transducer, a two wire interface, a microprocessor, a digital to analog converter, a first control circuit, and a second control circuit. A current passing through the two wire interface indicates a condition of the transducer. The microprocessor is interfaced with the transducer. The digital to analog converter receives a signal from the microprocessor indicating a current value. The first control circuit is coupled to the digital to analog converter and adapted to control the current passing through the two wire interface to the current value. The second control circuit is coupled to the digital to analog converter and supplies current to a secondary load.

Abstract: Systems and methods for inaudible enhanced pulse width modulation (PWM) backlight dimming are provided. By way of example, an electronic display backlight system according to the present disclosure may include a backlight element and backlight driver circuitry. The backlight driver circuitry may drive the backlight element at various brightness levels using at least two individual duty cycles that occur immediately after one another. The backlight driver circuitry may vary the individual duty cycles such that none will ever reach 100% unless all are 100%, thereby preventing the occurrence of audible noise that might otherwise arise if an “on” PWM period from one individual duty cycle continued into the next.

Abstract: Circuits for sensing current levels within an apparatus are disclosed. In specific cases, a constant voltage power supply is used to power an LED lighting apparatus in which there are uncertainties within the forward voltages of the LEDs, which in turn creates uncertainty with respect to the current level flowing through the LEDs. To manage these uncertainties, the current flowing through the LEDs is measured by determining a voltage level across a known resistor and calculating the current level. To prevent the known resistor from causing a significant reduction in the efficiency of the overall light engine, the circuit includes one or more transistors in parallel with the known resistor to reduce the effective resistance in the LED circuit during times that the current is not being sensed.

Abstract: A lighting system includes one or more methods and systems to control dissipation of excess power in the lighting system when the power into a switching power converter from a leading edge, phase-cut dimmer is greater than the power out of the switching power converter. In at least one embodiment, the lighting system includes a controller that controls dissipation of excess energy in the lighting system to prevent a premature disconnection of the phase-cut dimmer. In at least one embodiment, the controller actively controls power dissipation by generating one or more signals to actively and selectively control power dissipation in the lighting system. By actively and selectively controlling power dissipation in the lighting system, the controller intentionally dissipates power when the power into the lighting system should be greater than the power out to a lamp of the lighting system.

Abstract: A fault mode of a PWM module embedded in a microcontroller is used to detect main supply zero crossings for regulating output voltage of a PFC converter operating in BCM, without using an external detecting element or a comparator, ADC or other specialized component internal to the microcontroller. In some implementations, the end of decrease current flow in the energy storage inductor of the converter is used to reinitialize a PWM timer or counter (counting-up or counting-down timer). The current goes to zero for a time period when the main supply voltage goes to zero, resulting in the PWM timer or counter not being reinitialized prior to the end of the current PWM cycle. The failure to reinitialize the timer or counter can be used to generate a signal indicative of a zero voltage crossing of the main supply voltage.

Abstract: A load driving apparatus related to light emitting diodes (LED) is provided. The load driving apparatus includes a power conversion circuit, a complex function circuit, and a control chip. The power conversion circuit receives a DC input voltage and provides a DC output voltage to at least one LED string in response to a gate pulse-width-modulation (PWM) signal. The complex function circuit is serially connected with the LED string and provides a short-protection mechanism. The control chip is coupled to the power conversion circuit and the complex function circuit. The control chip generates the gate PWM signal to control the operation of the power conversion circuit, and when the LED string is short-circuited, the control chip controls the complex function circuit to activate the short-protection mechanism, so as to protect the load driving apparatus from being damaged.

Abstract: A power supply topology is used in which a transistor is provided on the side of an output node of a rectifying circuit. An inductor is provided on the side of a reference node, a resistor is inserted between the transistor and the inductor, and one end of the resistor is coupled to a ground power supply voltage of a PFC circuit. The PFC circuit includes a square circuit which squares a result of multiplication of an input voltage detection signal and feedback information (output voltage of an error amplifier circuit). The PFC circuit drives on the transistor when a detection voltage developed at the resistor reaches zero, and drives off the transistor when the detection signal reaches an output signal of the square circuit.

Abstract: Representative embodiments of the invention provide a system, apparatus, and method of controlling an intensity and spectrum of light emitted from a solid state lighting system. The solid state lighting system has a first emitted spectrum at a full intensity level and at a selected temperature, with a first electrical biasing for the solid state lighting system producing a first wavelength shift, and a second electrical biasing for the solid state lighting system producing a second, opposing wavelength shift. Representative embodiments provide for receiving information designating a selected intensity level or a selected temperature; and providing a combined first electrical biasing and second electrical biasing to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum over a predetermined range of temperatures.

Abstract: The invention relates to a method for operation of an actively clocked PFC circuit with a directly or indirectly connected load circuit at the output of the PFC circuit, wherein the load circuit has a lighting means, in particular one or more LEDs, wherein the PFC circuit is supplied at least with a measurement signal which reflects the power consumption of the load circuit or with an external control signal which indicates the power consumption, and a control circuit adjusts the mode of operation of the PFC circuit continuously or preferably in two or more steps, depending on the control signal or measurement signal.

Abstract: A 4 pin LED retrofit lamp for replacement of socket fitted CFL lamp driven by fluorescent ballast is provided. The retrofit lamp comprises a plurality of LEDS in connection with the fluorescent ballast. The circuit of the lamp comprises a bridge rectifier that converts the AC waveform into DC and a capacitor to filter the resulting waveform.

Abstract: A circuit for driving multiple light emitting diodes (LEDs) includes at least two sets of LEDs, each set comprised of one or more LEDs in series. The circuit further includes a single inductor connected in series with the two sets of LEDs. At least one set of LEDs is connected to a shunting transistor connected in parallel with the set of LEDs. The duty cycle of the shunting transistor is controlled by a single controller connected to the shunting transistor and the inductor.

Abstract: A driving circuit for a LED backlight module includes a brightness adjusting module, a current detector, a reference voltage adjusting module, and a comparing module. The current detector is capable of detecting the current of the brightness adjusting module and outputting a detecting result. The reference voltage adjusting module is capable of choosing the corresponding reference voltage corresponding to the detecting result of the current detector. Thus, the reference voltage outputted to the comparing module can be adjusted according to the change of the current of the brightness adjusting module. This reduces the power consumption and the amount of heat generated due to the power consumption, and improves the performance of the LED backlight module.

Abstract: In various embodiments, a method for powering light sources from a input power supply through a converter circuit is provided including a primary side and a secondary side separated by a galvanic barrier, wherein the primary side includes a power factor control block with an output capacitor. The method may include providing save circuitry on said secondary side for saving operational data of the converter upon failure of said input power supply; and powering said save circuitry during saving said operational data with energy derived from said output capacitor of said power factor control block.

Abstract: A lighting system and method are provided for controlling a PWM duty cycle. The lighting system is provided with at least one device that is configured to emit light in response to receiving electrical power. The lighting system includes a power circuit and a feedback circuit. The power circuit is configured to selectively supply power to the device at a duty cycle corresponding to a first mode and a second mode, wherein the duty cycle of the first mode is less than 10% of the duty cycle of the second mode. The feedback circuit is configured to provide a feedback signal that is indicative of the energy provided to the device. The power circuit is further configured to disable power to the device during the first mode in response to the energy being greater than a threshold energy value, thereby adjusting the duty cycle.

Abstract: A PFC LED driver capable of reducing flicker, including: a bridge rectifier, used to generate a full-wave-rectified line input voltage according to an AC power a single stage PFC constant average current converter, coupled with the bridge rectifier and used for forcing an input current to track the full-wave-rectified line input voltage and regulating an average value of an output current at a first preset value; and a peak current regulator, in series with an LED module to form a load for the output current to flow through, wherein the peak current regulator is used to regulate a peak of the output current at a second preset value, and the second preset value is higher than the first preset value.

Abstract: In one embodiment, an LED driving circuit can include: (i) a sense circuit configured to sense an inductor voltage, and to generate a sense voltage signal; (ii) a protection control circuit configured to activate a first protection control signal in response to a comparison of the sense voltage signal against a first reference voltage to indicate an LED device is in a first load state; (iii) the protection control circuit being configured to activate a second protection control signal in response to a comparison of the sense voltage signal against a second reference voltage to indicate the LED device is in a second load state; and (iv) a PWM control circuit configured to control a power switch according to the first protection control signal or the second protection control signal, based on the load state of the LED device.

Abstract: A light emitting diode (LED) lighting system includes a switching power converter having an input for coupling to an alternating current (AC) power source, an output, and a switch. The LED lighting system also includes an LED lighting subsystem coupled to receive power from the output of the switching power converter. The LED lighting subsystem includes a current source for one or more LEDs, and the current source has a control node and a sense node. The LED lighting system additionally includes a switch state controller coupled to the switching power converter and coupled to the LED lighting subsystem. The switch state controller controls switching of the switch and varies a control current provided to the control node of the current source based on at least a parameter sensed from the sense node.

Abstract: A safety flashing detector that suitably detects unintentional flashing of the LED light engine in a traffic lamp is provided. The LED light engine may flash unintentionally when there are failures (hardware or software) inside a traffic lamp. In certain embodiments, unintentional flashing may be detected using a current sensor. If unintentional flashing is detected, the flashing detector may activate and shut down the LED light engine to remove the hazardous failure and eventually triggers the fuse blowout circuit. Hardware circuitry is suitably employed for both reliability and safety purposes, but software may also be employed.

Abstract: Provided is a lamp ballast having a filament heating apparatus for gas discharge lamp, including a PFC converter for receiving an AC input voltage and converting the AC input voltage into a DC bus voltage; an inverter connected to an output end of the PFC converter for converting the DC bus voltage into an AC output voltage for driving gas discharge lamps; and a filament heating apparatus connected to the output end of the PFC converter. The filament heating apparatus includes an auxiliary heating circuit for converting the DC bus voltage into a heating power for pre-heating the filaments of the gas discharge lamps; and a control circuit connected to the inverter and the auxiliary heating circuit for generating an auxiliary voltage according to the heating power to activate the PFC converter.

Abstract: For the purpose of power factor correction of an operating device for a lamp, an inductor (7) is supplied with an input voltage (Vin), a controllable switch element (13) coupled with the inductor (7) being opened or closed to optionally charge or discharge the inductor (7). A control unit (14) for controlling the switch element (13) is designed such that it determines, depending on an output voltage (Vout) of the power factor correction circuit, a switch-on time (Ton) for switching the switch element (13) on and controls the switch element (13) optionally according to at least a first operating mode and a second operating mode, the operation in the first operating mode and the operation in the second operating mode being dependent on the duration of the determined switch-on time (Ton).

Abstract: An LED lighting device including a DC power source circuit, a high frequency generation circuit which includes an inverter circuit having switching elements and a resonance circuit having a series-connected inductor and condenser, in which the switching elements are on-off controlled by a no-load resonance frequency of the resonance circuit, and DC voltage input from the DC power source circuit is converted into a high frequency AC voltage, a rectification smoothing circuit having an input side which is connected between both edges of the condenser or both edges of the inductor; and a light emitting diode series connected to an output side of the rectification smoothing circuit.

Abstract: An LED driving device that performs a dimming operation of an LED module, the device includes: a dimming controller that receives the dimming instruction signal and generates a dimming signal; and a driving circuit that supplies an output current to the LED module based on the dimming signal generated by the dimming controller, wherein the driving circuit unit includes: a converter controller that generates a drive signal based on the dimming signal and outputs the drive signal to a first switching element; a first current setting circuit; and a second current setting circuit that is connected in parallel to the first current setting circuit, and wherein the dimming controller controls an operating state of the second current setting circuit to switch an adjustment range of the output current and a change characteristic of the output current in response to the dimming signal.

Abstract: A backlight driving circuit is disclosed. The backlight driving circuit includes a boost circuit, a constant-current driving chip, a detecting module and a LED string coupled with the boost circuit. The boost circuit boosts an input voltage and then provides the boosted voltage to the LED string. The detecting module receives and calculates external PWM optical signals to obtain a duty-cycle ratio of the PWM optical signals, and compares the duty-cycle ratio of the external PWM optical signals with a predetermined threshold to determine if control signals have to be generated for the constant-current driving chip such that the constant-current driving chip controls the current passing through the LED string. The backlight driving circuit can operate normally even when the duty-cycle ratio of the PWM optical signals is very small. In addition, a liquid crystal display includes the above backlight driving circuit is also disclosed.

Abstract: A light emitting diode (LED) driver circuit that generates current for driving an LED load includes a voltage converter circuit configured to supply a drive current to the LED load in response to a control signal, a control circuit that generates the control signal, and a bias voltage generating circuit that generates the bias voltage for the control circuit. The bias voltage generating circuit is galvanically isolated from a power supply voltage and from the LED load. The voltage converter circuit regulates a level of the drive current supplied to the LED load in response to the control signal.

Abstract: A digital compensator detects time-varying or periodic variations in the input voltage and, via the use of an iterative-learning control (“ILC”) system, a repetitive-control (“RC”) system, or a run-to-run control (“R2R”) system, generates a compensating signal based on prior behavior of the time variance.

Abstract: The present invention relates to a control circuit for an illuminating device, characterized in that the control circuit comprises a detecting unit, a central control unit and an illumination mode control unit, the detecting unit detects ambient brightness and generates a detection signal, the central control unit controls the illumination mode control unit, according to the detection signal, to generate a plurality of first driving signal enabling the illuminating device to operate in a first illumination mode or a plurality of second driving signal enabling the illuminating device to operate in a second illumination mode. The control circuit can automatically adjust the illuminating device to be in different operation modes according to different ambient brightness.

Abstract: A representative apparatus controls current supplied to solid state lighting, such as light emitting diodes. The apparatus includes an inductor, a memory adapted to store a plurality of current parameters and a controller. The controller is configured to control a power source to supply current to the inductor to start an energizing cycle, monitor an inductor current level, reduce the inductor current level in response to the inductor current level reaching a predetermined peak inductor current, and increase the inductor current level in response to the inductor current reaching a predetermined minimum current is reached. In at least one embodiment, the controller modulates a current provided to the solid state lighting such that a DC average current level is substantially proportional to one-half of a sum of the predetermined peak current level and the predetermined minimum current level.

Abstract: For the purpose of power factor correction, an inductance (21) is supplied with an input voltage (Vin), wherein a controllable switching means (24) that is coupled to the inductance (21) is actuated in order to selectively charge and discharge the inductance (21). A control device (14) for actuating the switching means (24) is designed such that it actuates the switching means (24) selectively on the basis of one of a plurality of modes of operation. In a first mode of operation, a switch-on time is stipulated for the switching means (24) on the basis of a minimum waiting time and on the basis of a voltage that drops across the switching means (24).

Abstract: A light emitting diode (LED) lighting system includes a power factor correction (PFC) controller that determines at least one power factor correction control parameter from phase delays of a phase modulated signal. In at least one embodiment, a peak voltage of the phase modulated signal is a PFC control parameter used by the PFC controller to control power factor correction and generation of a link voltage by a PFC LED driver circuit. The phase delays. are related to a peak voltage of the phase modulated signal. Thus, in at least one embodiment, detecting the phase delay in one or more cycles of the phase modulated signal allows the PFC controller to determine the peak voltage of the phase modulated signal.

Abstract: A ballast configured to connect to a set of lamps to energize the set of lamps is provided. The ballast comprises an inverter circuit for generating an oscillating power signal, wherein the oscillating power signal has a frequency, and a resonant tank circuit electrically connected to the inverter circuit for receiving the oscillating power signal and therefrom providing a lamp current to the set of lamps. A resistance circuit is connected to the inverter circuit. The resistance circuit has a resistance that defines the frequency of the oscillating power signal generated by the inverter circuit. A current control circuit is connected to the resistance circuit for adjusting the resistance of the resistance circuit as a function of a number of lamps that are connected to the ballast.

Abstract: An LED light-adjustment driver module includes a duty cycle detection unit, a current output unit, a comparator and a capacitor unit. The first input end of comparator is connected to capacitor unit, and the second input end of comparator inputs a default threshold voltage. The duty cycle detection unit is for receiving externally inputted PWM signal and detecting the duty cycle of the PWM signal; when the duty cycle detection unit detects the duty cycle is less than a default threshold, the current output unit increases the output current or the capacitor unit reduces the capacitance provided to reduce the time for the voltage of the capacitor unit to reach the threshold voltage. Hence, the charging speed of the capacitor unit can be increased.

Abstract: A system for implementing mains-voltage-based dimming of a solid state lighting module includes a transformer, a mains sensing circuit and a processing circuit. The transformer includes a primary side connected to a primary side circuit and a secondary side connected to a secondary side circuit, the primary and second side circuits being separated by an isolation barrier. The mains sensing circuit receives a rectified mains voltage from the primary side circuit and generates a mains sense signal indicating amplitude of the rectified mains voltage. The processing circuit receives the mains sense signal from the mains sensing circuit across the isolation barrier, and outputs a dimming reference signal to the secondary side circuit in response to the mains sense signal. Light output by the solid state lighting module, connected to the secondary side circuit, is adjusted in response to the dimming reference signal output by the processing circuit.

Abstract: The invention relates to supervision circuits (10) for supervising organic light emitting diode devices (1) via detection circuits (20) for detecting failure states of the organic light emitting diode devices (1) and for generating decision signals in response to detected failure states of the organic light emitting diode devices (1), which detected failure states have durations equal to or larger than time intervals. In response to the decision signals, the organic light emitting diode devices (1) can be bypassed and deactivated through switching circuits (30) such as bi-stable circuits. The failure states may include that the organic light emitting diode devices (1) have a relatively low impedance or “short” and a relatively high impedance or “open”. The supervision circuit (10) further prevents the organic light emitting diode devices (1) from being bypassed unjustly.

Abstract: An LED lighting system is provided. The LED lighting system includes a main transformer, a voltage detector, a current controller, a second reference voltage supplier, and a power factor compensation circuit. The main transformer transforms an input signal to supply the transformed input signal to an LED group. The voltage detector supplies a control voltage proportional to a level of an input voltage corresponding to the input signal. The current controller includes a first voltage storage, a negative voltage applier, a second voltage storage, switch, and a current control signal generator. The first voltage storage stores the control voltage supplied from the voltage detector or discharges a stored voltage. The negative voltage applier is connected to the first voltage storage, and connected to a ground to apply the control voltage to the ground when the control voltage is a negative voltage.

Abstract: The disclosed multi-channel driver equalizer circuit matches currents in multiple strings of illumination devices at low current levels by using an analog equalizer to sequentially couple the output of a reference amplifier in series with each current source amplifier in a current limit loop of the driver equalizer circuit to correct the offsets of the current source amplifiers, resulting in the matching of string currents on average.

Abstract: A light emitting diode (LED) lighting system includes a PFC and output voltage controller and a LED lighting power system. The controller advantageously operates from an auxiliary voltage less than a link voltage generated by the LED lighting power system. The common reference voltage allows all the components of lighting system to work together. A power factor correction switch and an LED drive current switch are coupled to the common reference node and have control node-to-common node, absolute voltage that allows the controller to control the conductivity of the switches. The LED lighting system can utilize feed forward control to concurrently modify power demand by the LED lighting power system and power demand of one or more LEDs. The LED lighting system can utilize a common current sense device to provide a common feedback signal to the controller representing current in at least two of the LEDs.

Abstract: A dimmable LED driver adapted to be operated with a dimmer that is configured to generate a predetermined conductive angle, wherein the dimmable LED driver comprises: a rectifier configured to convert an alternating current output by the dimmer to a direct current, a buck PFC block configured to adjust an output voltage of the direct current so as to obtain a stable output voltage, a second buck DC/DC block configured to realize output of a constant current after the stable output voltage is realized, a dimming block configured to, after realizing output of the constant current, accomplish a dimming function jointly with the second buck DC/DC block, and an MCU configured to control the buck PFC block, the second buck DC/DC block and the dimming block.

Abstract: A method of driving a light source includes outputting a variable driving voltage to a light source part, sensing a first voltage based on the driving voltage and developed at a first end of the light source part, sensing a second voltage developed at a second end of the light source part due to current passing through the light source part and adjusting the driving voltage while using the first and second voltages so that power consumption by the light source part is substantially constant irrespective of temperature of the light source part and/or irrespective of a duty cycle ration being used to drive the light source part. Thus, a luminance of the light source part may be maintained at substantially uniform levels.

Abstract: A ceiling lamp adopting a non-separating driver circuit includes a conversion module and a control module. The conversion module converts an input voltage into an operating voltage to drive the LEDs and forming a driving current, and the control module monitors the operating voltage and the driving current to adjust the operating cycle of the conversion module, change the output voltage value of the operating voltage, and linearly change the driving current at a constant current state. The conversion module just executes the power conversion for one time to provide the driving power of the LEDs instead of using the conventional driving method that executes a two-stage power conversion by a separating power converter and a negative booster of the conventional ceiling lamp. Therefore, the ceiling lamp adopting a non-separating driver circuit is capable of lowering the circuit cost and improving the operating efficiency.

Abstract: A luminary dimming system having a three terminal dimming unit. The dimming unit includes a power controller and a receiver and is responsive to dimming directives received by the receiver. The power controller controls a buck switch and a freewheel switch in a manner that allows reduction of alternating current voltages. Such voltage reduction is accomplished in a manner that preserves the waveform of the source voltage and the power factor exhibited by the luminary.

Abstract: System and method for dimming control. The system includes a system controller including a first controller terminal and a second controller terminal, a transistor including a first transistor terminal, a second transistor terminal and a third transistor terminal, and a resistor including a first resistor terminal and a second resistor terminal. The system controller is configured to generate a first signal at the first controller terminal based on an input signal and to generate a second signal at the second controller terminal based on the first signal. The first transistor terminal is coupled to the second controller terminal. The first resistor terminal is coupled to the second transistor terminal. The second resistor terminal is coupled to the third transistor terminal. The transistor is configured to receive the second signal at the first transistor terminal and to change between two conditions in response to the second signal.