Abstract: Circuits and methods to prevent ringing of white LED drivers by adding a high voltage coil switch circuit, a high voltage edge detector circuit, and a boot strap circuit are disclosed. The coil switch circuit to short the coil of a boost converter when the current in it reaches zero during DCM, comprises a series of 2 identical HV enhancement NMOS with bulk switch system. The Edge Detector circuit senses the fast falling edge of the LX node. The Boost Strap circuit lifts the gate of coil switch circuit above the battery voltage level and turns on the coil switch.

Abstract: A serial-type LED device includes p light source units and a dimming circuit. Each light source unit includes a first and a second terminals, m light strings and m current balance units. Each light string includes LEDs coupled in series to have a first terminal coupled to the first terminal of a corresponding light source unit and a second terminal coupled to the second terminal of the corresponding light source unit through a corresponding current balance unit. The first terminal of the first light source unit is coupled to a second DC voltage, and the second terminal of the i-th light source unit is coupled to the first terminal of the (i+1)-th light source unit, where m and p are integers greater than or equal to 2 and i is any integer from 1 to (p?1). The dimming circuit coupled to the second terminal of the p-th light source unit controls the second DC voltage according to a current outputted from the p-th light source unit.

Abstract: An energy-saving illumination apparatus adapted to receive an input power includes a light unit, a detection unit, a dimming unit, and a control unit. The light unit has a plurality of light sets and a switch unit connecting the light sets in parallel and/or serial connections. The detection unit is for detecting the status of the input power. The dimming unit is for controlling the current of the light unit. The control unit is for controlling the switch unit according to the detection result of the detection unit and making the turn-on voltage of the light unit be changed along with the input power. The control unit controls duty cycle of pulse width modulation (PWM) signal and transmits the PWM signal to the dimming unit. The dimming unit adjusts the current which conducts and makes the light unit emit light to be changes along with the duty cycle.

Abstract: Each of blocks includes an arbitrary number of series connections of LEDs. A current signal for controlling operation of the LEDs in the blocks is divided into plural signal currents. An allowable forward current having a duty cycle corresponding to a division number is caused to flow through the LEDs in one block for an allowable time, using one of the signal currents. A rated forward current that does not cause destruction of LEDs is caused to flow through the LEDs in the other blocks, using the other of the signal currents. The LEDs in the blocks are driven by causing the allowable forward current and the rated forward current to flow periodically. The rated forward current is caused to flow through at least one additional LED, whereby a difference between respective voltages corresponding to the allowable forward current and the rated forward current is produced.

Abstract: A system including a selection module to select one of a plurality of templates corresponding to a plurality of light emitting diodes, where the selected template includes one or more of temperature, current, and voltage characteristics of the plurality of light emitting diodes. A control module measures a voltage across one of the plurality of light emitting diodes; determines a temperature of the plurality of light emitting diodes based on the voltage measured across the one of the plurality of light emitting diodes and the selected template; and in order to maintain a luminosity of the plurality of light emitting diodes at a predetermined luminosity, adjusts current through the plurality of light emitting diodes based on the temperature, the selected template, and calibration data. The calibration data include current through the plurality of light emitting diodes and corresponding luminosities of the plurality of light emitting diodes.

Abstract: A lighting device includes a DC/DC power converter, a controller/processor electrically connected to the DC/DC power converter, a light emitting diode (LED) current control circuit communicably coupled to the controller/processor and electrically connected to the DC/DC power converter, and two or more LEDs comprising at least a first color LED and a second color LED electrically connected to the LED current control circuit. The LED current control circuit provides an on/off signal having a cycle time to each LED in response to one or more control signals received from the controller/processor such that the two or more LEDs produce a blended light having a specified color based on how long each LED is turned ON and/or OFF during the cycle time.

Abstract: There is provided a light emitting diode driving apparatus capable of uniformly maintaining current balance between light emitting diode channels. The light emitting diode driving apparatus includes: a DC to DC converting unit converting the direct current power into settable driving power; a detecting unit detecting voltage drops generated in each of a plurality of light emitting diode channels each having a plurality of light emitting diodes; a converting unit converting an analog value into a digital value; and a driving unit differentially setting duty cycles of switching signals according to the digital values from the converting unit to drive the plurality of light emitting diode channels.

Abstract: A Christmas strip lighting control system, having a main structure composed of a switching power supply and a programmable lighting control system, and operates in coordination with a micro controller unit to form the Christmas strip lighting control system applicable for use in LED strip lighting sets providing diversified output types. The present invention not only reduces the number of components needed, achieving more extensive adaptability and more convenient production to benefit protecting the green environment, but also provides accurate control over output power, enables more stable effectiveness, reduces failure rate to the minimum and prolongs serviceable life.

Abstract: A DC-DC converter supplies an output voltage to a plurality of channels of a light emitting device array in common. A current driver has a plurality of driver units which drive the channels. Each of the driver units includes a drive transistor and a detector which detects an abnormality of a drive current. A logic unit generates digital data in response to a plurality of detection signals and supplies the same to a D/A converter. An analog reference voltage of the D/A converter is supplied to the DC-DC converter. The logic unit executes a calibration operation which determines digital data for setting the minimum output DC voltage at the normal operation of all the channels by sequential updating of the digital data.

Abstract: A backlight unit includes light source units which emit light, and light source driving integrated circuits which control a brightness of the light source units, respectively. Each of the light source driving integrated circuits includes a current generator which generates a first current and a second current, a current level controller which controls a current value of the first current in response to duty ratio information of a pulse width modulation signal, a voltage supply unit which outputs a voltage corresponding to the second current, an output buffer unit which outputs the voltage from the voltage supply unit, and a driving switch unit which drives the light source units to allow a current corresponding to the voltage provided from the output buffer unit to flow through the light source units, where current values of the second current and the first current are the same as each other.

Abstract: A multi-state switch network is provided that includes a serially connected diode pair configured to receive a single control signal at a control node. The serially-connected diode pair is configured to control a pair of switches. Moreover, the single control signal is operative to drive the serially connected diode pair to a first state, a second state, or a third state based at least in part on a state of the single control signal. Furthermore, the single control signal is operative to alternatively turn ON a first diode of the diode pair and turn OFF a second diode of the diode pair when the state of the single control signal is a first state, turn OFF the first diode and turn ON the second diode when the state of the single control signal is a second state, and turn OFF the first diode and turn OFF the second diode when the state of the single control signal is a third state.

Abstract: Exemplary systems, methods and apparatuses for a distributed solid-state lighting system are disclosed. An exemplary apparatus includes a plurality of light emitting diodes; a plurality of first switches to switch a selected segment of light emitting diodes into or out of a series light emitting diode current path; a first terminal controller to control switching of corresponding segments of light emitting diodes into the series light emitting diode current path; a second switch coupled in series with each segment of light emitting diodes; and a second terminal controller to turn the second switch on and off at a frequency generally at least about four to one thousand times the AC line frequency or in response to a random or pseudo-random signal.

Abstract: A backlight apparatus includes light emitting diode (LED) modules. Each LED module includes a first connection pin set, a second connection pin set, a driving circuit, a first LED string, and a second LED string. Each of the connection pin sets has a first and second power connection pins and a first and second ground connection pins. The first and second power connection pins are coupled to each other, and the first and second ground connection pins are coupled to each other. The first ground connection pin of the first connection pin set is coupled to the first power connection pin of the second connection pin set. The driving circuit is used to provide a driving signal. Each of the LED strings is serially connected between the second power connection pin and the second ground connection pin of each of the connection pin sets and receives the driving signal.

Abstract: Systems and methods for using an expert system to develop a color model for and LED-based lamp for reproducing a target light and calibrating the lamp are disclosed. The CCT of light generated by the lamp is tunable by adjusting the amount of light contributed by each of the LED strings in the lamp. The target light is decomposed into different wavelength bands, and light generated by the LED-based lamp is also decomposed into the same wavelength bands and compared. A color model for the lamp provides information on how hard to drive each LED string in the lamp to generate light over a range of CCTs, and the color model is used to search for the appropriate operating point of the lamp to reproduce the target light.

Abstract: An LED fixture is disclosed. The fixture includes an LED array having at least one LED, a first LED driver which is a lower intensity driver and a second LED driver which is a higher intensity driver. The LED drivers and the LED array are electrically connected in parallel to each other and the LED drivers are capable of simultaneously and continuously supplying power to each LED in the LED array.

Abstract: The present invention relates to a light-emitting diode (LED) driving circuit for lighting, which divides a specific pattern of driving data for a number of sections within one period or a half period of driving power, stores the divided data in a driving data storage device, and drives LEDs connected in series in an LED array unit using the driving data so as to drive the LEDs with high efficiency, a high power factor, and low total harmonic distortion (HTD).

Abstract: An LED driver system including an input receiving a rectified AC conductive angle modulated voltage on a rectified node, a converter, a low-pass filter, and AC detector, and a driver network. The converter is to the rectified node and includes a power switching device coupled to a switching node, in which the power switching device is controlled to convert the rectified AC conductive angle modulated voltage to an output voltage and output current. The low-pass filter is configured to filter voltage of the switching node to provide a filtered voltage. The AC detector receives the filtered voltage and provides a current sense signal indicative thereof. The driver network controls duty cycle of the power switching device based on the current sense signal.

Abstract: Apparatus and associated methods reduce harmonic distortion of a excitation current by diverting the excitation current substantially away from a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level, and ceasing the current diversion while the excitation current or voltage is substantially above the predetermined threshold level. In an illustrative embodiment, a rectifier may receive an AC (e.g., sinusoidal) voltage and deliver unidirectional current to a string of series-connected LEDs. An effective turn-on threshold voltage of the diode string may be reduced by diverting current around at least one of the diodes in the string while the AC voltage is below a predetermined level. In various examples, selective current diversion within the LED string may extend the input current conduction angle and thereby substantially reduce harmonic distortion for AC LED lighting systems.

Abstract: The invention relates to a LED circuit arrangement (1) with at least a voltage input (4), adapted to provide an operating voltage, a reactive element (6) connected in series with said voltage input (4) and a LED light source (3). To enable the LED circuit arrangement (1) to be driven at an operating voltage, the LED light source (3) comprises a first and a second LED unit (8, 9), each having one light emitting diode, controllable switching means (10) to connect said LED units (8, 9) with said reactive element (6) in a low voltage mode and a high voltage mode and a control unit (12). The LED light source (3) shows a first forward voltage in said low voltage mode and a second forward voltage in said high voltage mode, said second forward voltage being higher than said first forward voltage.

Abstract: A driving circuit, comprising a power supply, a transistor unit and a feedback control circuit, is disclosed. The power supply is adaptor to provide an electric power to drive a load. The transistor unit comprises at least one load coupling end to couple to the load for adjusting an amount of current flowing through the load. The feedback control circuit controls an amount of the electric power provided by the power supply according to a voltage level of the least one load coupling end. Wherein, the feedback control circuit comprises an error amplifying circuit and a feedback control switch. The error amplifying circuit generates an error amplified signal according to the voltage level of the least one load coupling end, and the feedback control switch is coupled to an output of the error amplifying circuit and is switched between a turn-on state and a turn-off state based on a dimming signal.

Abstract: Improved circuits minimize, or eliminate, energy losses in the supply of energy to control LEDs. Diodes and a capacitor reduce or eliminate LED blinking, and create smooth and continuous, infinitely variable dimming. The components are added to supply power to each LED during the half of the AC cycle where it would normally be turned off. A first added diode allows an added capacitor to charge during the half cycle that the original diode is turned on, but does not allow the other half cycle to discharge the added capacitor. When the added capacitor is charged enough to turn on the original diode, it stays on throughout the AC cycle. The same relationship exists between the second added diode, the added capacitor and the second original diode. Zener diodes protect the LEDs from voltage surges/spikes by shunting current around LEDs when the voltage exceeds the Zener diode's breakdown voltage.

Abstract: Circuits for controlling a plurality of LEDs connected in series are disclosed herein. The circuit includes a plurality of switches, wherein each switch is connectable between the anode and cathode of one of the plurality of LEDs. Each of the switches has a first state wherein current does not pass through the switch and a second state wherein current passes through the switch. The circuit also includes an input for receiving data to program the switches and a data line for transferring data between a circuit controlling second LEDs that are connected in parallel with the first LEDs and the circuit. In addition, the circuit includes a data output for transferring data to other circuits controlling third LEDs that are connected in series with the first LEDs.

Abstract: A light system that is controllable to generate a plurality of selected lighting effects, the light system includes a main processor, the main processor being in communication with a plurality of light sources; and each of the plurality of light sources having a distinct, known address whereby one of more of the light sources are individually addressable by the main processor, a known address being received by a selected light source of the plurality of light sources and acting to set the selected light source of the plurality of light sources in a disposition to receive a subsequent command from the main processor for generating a selected lighting effect. A light source and a method of forming a light system are further included.

Abstract: A light emitting element driving device, which flashing-drive a plurality of light emitting element arrays connected in parallel by switching elements connected in series with each of the plurality of light emitting element arrays, the light emitting element driving device including: a current detection unit configured to detect respective currents flowing through each of the plurality of light emitting element arrays as currents of the light emitting element arrays; a selection unit configured to select the smallest current of the light emitting element arrays of the detected currents obtained by the current detection unit; and an output voltage control unit configured to control output voltage supplied to the plurality of light emitting element arrays so that the current of the light emitting element arrays selected by the selection unit becomes a preset reference current value.

Abstract: A light emitting device includes light emission units, a voltage generator, a lighting selector, and a drive control unit. Each light emission unit includes light emitting component groups each of which includes a light emitting component array and a drive switch. The light emitting component array includes light emitting components that are connected in series. The drive switch is connected in series to the light emitting component array to drive the light emitting component array. The lighting selector selects the light emitting component group that is to be lit on according to brightness intensity required for each light emission unit. The drive control unit controls each drive switch independently according to the selection by the lighting selector and controls to light on each light emitting component group independently and controls the voltage generator to generate a common drive voltage.

Abstract: Switching mode power supplies (SMPS) and control methods used thereof are disclosed. An exemplifying SMPS is coupled to control an inductive device. The SMPS comprises a voltage divider and a peak controller. The voltage divider comprises a resistor and a controllable resistor connected in series through a connection node. The resistance of the controllable resistor is variable, controlled by a control signal. The voltage divider generates a limiting signal at the connection node based on a line voltage at a line voltage power node. The peak controller controls a peak current flowing through the inductive device according to the limiting signal.

Abstract: A system controls a switching power converter to power LED strings using a predictive feedforward control mechanism. An LED controller determines programmed current levels and duty cycles for driving LED strings. The LED controller determines a predicted load for a subsequent cycle of a switching power converter driving the LED strings based on the programmed current levels and duty cycles. A power conversion controller uses the predicted load information to control switching of the switching power converter. This improves the dynamic response of the switching converter to changing load conditions, thereby improving overall power efficiency and performance of the system.

Abstract: A phase-shift dimming circuit for LED controller having a delay signal generator configured to receive a PWM input signal, and to provide a plurality of pairs of set signal and reset signal, the set signal and the reset signal respectively having pulses; and a plurality of latches configured to respectively receive the plurality of pairs of set signal and reset signal to generate a plurality of PMW output signals, each of the PWM output signals having pulses, and wherein the rising edge of the pulses of the PWM output signals is based on the corresponding set signal pulses, and the falling edge of the pulses of the PWM output signals is based on the corresponding reset signal pulses.

Abstract: A driving circuit for a single-string light-emitting diode (LED) lamp includes a push-pull converter. The push-pull converter converts an input low DC voltage (such as 12-19V) to a high DC voltage (such as above 200V) to supply power to the single-string LED lamp. The driving circuit controls a lamp current flowing through the single-string LED lamp by constant current and adjusts brightness of the single-string LED lamp by pulse-width modulation (PWM) dimming. In addition, the single-string LED lamp provides the standardization design for connectors of the driving circuit used to connect to the single-string LED lamp so that the driving circuit has a better common-use characteristic. Moreover, the driving circuit does not need a current balance circuit and only needs a cheaper and general-purpose integrated circuit to control the push-pull converter to reduce design cost of the driving circuit.

Abstract: According to the present invention, anode-side ends of LED arrays (1011) and (1012) are connected to an identical point. A constant current circuit (1003) drives the LED array (1011) by a constant current, whereas, a constant current control circuit (3) drives the LED array (1012) by a constant current and by pulses.

Abstract: A lighting apparatus includes a string of Light Emitting Diode (LED) sets coupled in series, each set including at least one LED, a light spreading circuit configured to incrementally turn on respective ones of the LED sets responsive to a power signal, and an energy storage module that is configured to store energy during a first interval of a period of the power signal and to apply the stored energy to the string during a second interval of the period of the power signal.

Abstract: A multi-channel LED driving system includes a power adapter, a rectifying and filtering unit, a plurality of LED strings, and a plurality of linear regulators, a CC/CV controller, an optically coupled isolator and a PWM controller. The CC/CV controller detects the conducting currents flowing though the LED strings and DC voltage source outputting from the rectifying and filtering unit, and provides voltage compensation of the power adaptor. In addition, the linear regulators slightly modulate the current difference between the LED strings to achieve current-sharing control, thus stabilize the illuminating brightness generating by the LED.

Abstract: A method for controlling a light emitting diode (LED) is provided. Initially, the LED, which had been active, is deactivated, and a voltage for a current that corresponds to the persistence of the LED is generated. The voltage is then integrated so as to generate an integrated voltage, and the integrated voltage is compared to a threshold. When the integrated voltage is less than the threshold, the LED is then activated.

Abstract: An LED driver controls current through an LED string. The LED driver generates a boosted PWM signal to drive a PWM transistor in the LED current path such that the PWM transistor maintains a substantially constant VGS, thus minimizing turn-on impedance of the PWM transistor. A current mirror circuit controls peak LED current when the PWM transistor is on. A trimming circuit includes a set of programmable switches to couple or decouple trimming transistor from the LED current path, and allowing for fine calibration of the LED current. By maintaining a low resistance and compensating for current mismatch in the LED current path, the LED driver provides efficient power performance and robustness that is particularly beneficial in high current applications.

Abstract: An LED driving device includes a rectifier circuit, a first LED module, a first switch, a second LED module, a second switch, and a diode module. The rectifier circuit includes a pair of input terminals and first and second output terminals for receiving an AC voltage and rectifying the AC voltage to output a pulsed rectified voltage. The first LED module and first switch connected in series are electrically connected between the first and second output terminals of the rectifier circuit. The second LED module and second switch connected in series are electrically connected between the first and second output terminals of the rectifier circuit. The diode module is connected between a common node of the first LED module and the first switch and a common node of the second LED module and the second switch.

Abstract: A light-emitting diode (LED) bulb has a shell and a base attached to the shell. An LED is within the shell. A driver circuit provides current to the LED. The driver circuit has a power factor control circuit that includes a tracking circuit configured to produce a tracking signal indicative of the voltage of the supply line. The power factor control circuit also includes a switch-mode power supply (SMPS) controller having an input pin and an output pin. The tracking circuit is connected to the input pin. Based on the signal at the input pin, the SMPS controller is configured to change a duty cycle of an output signal on the output pin.

Abstract: A light-emitting diode (LED) driver used to power at least one LED with an alternating current (AC) voltage source is provided. The LED driver includes a rectifying unit applying N-fold higher voltage than the voltage from the AC voltage source to the LED. The rectifying unit includes a first charging unit to charge a first voltage, and a second charging unit to charge a second voltage. The first voltage includes the voltage at the AC voltage source during a first half-cycle of one AC voltage cycle, and the second voltage includes the first voltage and the voltage at the AC voltage source during the second half-cycle of the AC voltage cycle. Accordingly, the LED driver may improve light-emitting efficiency and reduce flicker of LEDs.

Abstract: A series connected light string using LEDs connected to an AC power source is disclosed. In order to make some or all of the lights color change, twinkle, and/or flash, controllers are provided in series with all or some of the LEDs. Because the supply source AC, but the active elements are essentially rectifiers, the circuit becomes a half wave DC circuit. Half wave DC will cause unpredictable behavior in DC circuit components. This will cause the controller to shut down during the zero voltage portion of the pulsating DC cycle. To prevent this a current supplying element is placed in parallel with the controller.

Abstract: A LED current-balance driving circuit having a current-balance coil set, a switching unit, and a control circuit is provided. The current-balance coil set has at least a first coil and a second coil, both of which are in connection with respective LED strings, for balancing currents flowing through the LED strings. The switching unit and a leakage inductance of current-balance coil set are utilized to facilitate the voltage conversion for driving the LED strings. A duty cycle of the switching unit is controlled by the control circuit according to the currents flowing through the LED strings.

Abstract: Apparatus and associated methods involve operation of an LED light engine in which a relative intensities of selected wavelengths shift as a function of electrical excitation. In an illustrative example, current may be selectively and automatically diverted substantially away from at least one of a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level. The diversion current may be smoothly reduced in transition as the excitation current or voltage rises substantially above the predetermined threshold level. A color temperature of the light output may be substantially changed as a predetermined function of the excitation voltage. For example, some embodiments may substantially increase or decrease a color temperature output by a solid state light engine in response to dimming the AC voltage excitation (e.g., by phase-cutting or amplitude modulation).

Abstract: An LED drive circuit is disclosed, which comprises a square wave generator configured to generate a square-wave signal for driving an LED unit, an LLC resonance circuit configured to transform the square-wave signal outputted by the square wave generator into a sinuous wave of a reduced voltage level, and the LED unit comprising at least one LED sub-unit. The LED sub-unit comprises at least a first LED lamp set and a second LED lamp set connected in parallel, and LEDs of the first LED lamp set are disposed in a direction opposite to those of the second LED lamp set. The square wave generator, the LLC resonance circuit and the LED unit are connected in sequence. The LED drive circuit of the present disclosure can drive an LED and has a reduced cost.

Abstract: An adaptive switch mode LED driver provides an intelligent approach to driving multiple strings of LEDs. The LED driver determines an optimal current level for each LED channel from a limited set of allowed currents. The LDO driver then determines a PWM duty cycle for driving the LEDs in each LED channel to provide precise brightness control over the LED channels. Beneficially, the LED driver minimizes the power dissipation in the LDO circuits driving each LED string, while also ensuring that the currents in each LED string are maintained within a limited range. A sample and hold LDO allows PWM control over extreme duty cycles with very fast dynamic response. Furthermore, fault protection circuitry ensures fault-free startup and operation of the LED driver.

Abstract: Apparatus and associated methods reduce harmonic distortion of a excitation current by diverting the excitation current substantially away from a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level, and ceasing the current diversion while the excitation current or voltage is substantially above the predetermined threshold level. In an illustrative embodiment, a rectifier may receive an AC (e.g., sinusoidal) voltage and deliver unidirectional current to a string of series-connected LEDs. An effective turn-on threshold voltage of the diode string may be reduced by diverting current around at least one of the diodes in the string while the AC voltage is below a predetermined level. In various examples, selective current diversion within the LED string may extend the input current conduction angle and thereby substantially reduce harmonic distortion for AC LED lighting systems.

Abstract: A switch mode power supply (SMPS) converter is periodically run backwards by using a synchronous switch instead of the normally used commutating diode. By running the SMPS converter backwards the SMPS output capacitor can be discharged very quickly to provide a fast turn off of (no current through) the LED's, thereby solving the color shift problem. This enables positioning the output voltage of the SMPS up or down by actively charging or discharging the bulk output capacitor. Having the capability of actively charging or discharging the bulk output capacitor allows generation of a current source comprising substantially square, e.g., substantially full current when on and substantially no current when off, current pulses that are preferable for driving LED lighting applications.

Abstract: A voltage regulation circuit includes a voltage conversion module, an LED driving module and a control module. The voltage conversion module is operable to receive and convert the first voltage to a second voltage. Each LED driving loop of the LED driving module has a current regulator and an LED string. The control module is operable to output a control signal according to the received input signal which reflects the current flowing through the LED driving module. The voltage conversion module regulates the second voltage according to the control signal, such that the regulated second voltage still keeps the brightness of the LED string of each LED driving loop unchanged.

Abstract: An LED drive method is disclosed. In this way, the LED drive method allows not only the reference voltage to be periodically updated on the basis of the feedback drive voltages but also the drive voltage control signal to be generated using the updated reference voltage, in order to adjust the LED drive voltage applied to the LED array. Therefore, the LED drive circuit is hardly affected by the external environmental noise.

Abstract: A circuit for actuating a lighting module, comprising at least two semiconductor light-emitting elements (D1, D2) which are connected in series in a first operating mode; wherein, in the event of a predetermined threshold value for an operating voltage (101) being undershot, a second operating mode is detectable (102); and wherein, in the second operating mode, the at least two semiconductor light-emitting elements (D1, D2) are alternately actuable

Abstract: A color correcting device driver is configured to vary the equivalent current into light emitting elements (e.g., LEDs) with the frequency of the AC input current (e.g., 120 Hz). In implementations that include a fly-back controller with a power factor correction (PFC) controller on the primary side, the color correcting device driver performs the method of: 1) turning on the loads (e.g., white and CA strings of LEDs); 2) determining if the voltage supplied to the loads has dropped by a first threshold amount; 3) turning off the loads; and 4) determining if the voltage supplied to loads has recovered by a second threshold amount (or waiting for a fixed amount of time). The method is repeated. In implementations that do not include a PFC controller on the primary side, the color correcting device driver can create a pulse width modulated (PWM) signal.

Abstract: A device for controlling levels of light output by a solid state lighting load at low dimming levels includes a bleed circuit connected in parallel with the solid state lighting load. The bleed circuit includes a resistor and a transistor connected in series, the transistor being configured to turn on and off in accordance with a duty cycle of a digital control signal when a dimming level set by a dimmer is less than a predetermined first threshold, decreasing an effective resistance of the bleed circuit as the dimming level decreases.

Abstract: An arrangement wherein a plurality of LED strings are driven with a balanced drive signal, i.e. a drive signal wherein the positive side and negative side are of equal energy over time, is provided. In a preferred embodiment, the drive signal is balanced responsive to a capacitor provided between a switching network and a driving transformer. Balance of current between various LED strings is provided by a balancing transformer.