The present disclosure relates to current control circuitry for controlling a current through a load, the current control circuitry comprising: amplifier circuitry; reference voltage generator circuitry configured to supply a fixed reference voltage to a first input of the amplifier circuitry; an output stage comprising: a control terminal coupled to an output of the amplifier circuitry; a current input terminal configured to be coupled to the load; a current output terminal; a clock-controlled variable resistance coupled to the current output terminal of the output stage, wherein a resistance of the variable resistance is based on a digital code input to the variable resistance; and a feedback path between the current output terminal of the output stage and a second terminal of the amplifier circuitry for providing a feedback voltage to a second input of the amplifier circuitry.

A Light Emitting Diode (LED) light includes a bridge rectifier configured to be powered by an alternating current power source and to produce a rectified output. Control circuitry couples to the bridge rectifier and is configured to produce a shunt signal when the rectified output is less than a threshold voltage. A series connected Light Emitting Diode (LED) string includes a first group of LEDs and a second group of LEDs. A switch couples to a first side of the second group of LEDs and is controlled by the shunt signal to deactivate the second group of LEDs. The control circuitry may include a ratio metric series resistor string configured to sense a proportion of the rectified output and an inverter configured to generate the shunt signal based on the proportion of the rectified output.

A lighting unit (100) includes light emitting diode (LED) modules (120, 300) and a lighting driver (110, 200) connected to the LED modules. Each LED module includes LEDs (323) and an identification current source (324) supplying an identification current to an identification current output node (180, 380). All of the identification current output nodes are connected together to supply a total identification current having a magnitude which changes in response to the number of LED modules that are connected to the lighting driver. The lighting driver includes: a controllable current source (220 & 250) to supply an LED driving current to the LEDs of the LED modules, and a controller (230) that responds to the total identification current to control the controllable current source to supply the LED driving current at a magnitude which changes in response to the number of LED modules that are connected to the lighting driver.

The present invention relates to a busbar current control circuit, a constant current drive controller and an LED light source, wherein the busbar current control circuit comprises a branch resistor, a branch capacitor and a branch current source, the branch resistor and the branch capacitor are connected in parallel to form a branch, one end of the branch is connected a position between the busbar resistor and the load, and the other end is connect to the branch current source; the branch current source outputs to the branch a current of adjustable magnitude, the sum of the voltage on the busbar resistor and the voltage on the branch resistor remains constant. Wherein the branch resistor occupies a portion of the voltage of the busbar resistor so that the magnitude of the current output by the busbar changes continuously, that is, when the current flowing into the branch increases, the voltage occupied by the branch resistor increases and the voltage on the busbar resistor decreases, so as to reduce the current on the busbar. Since the branch current is smoothly adjusted by the branch current source, the regulation of the output current on the busbar is also smooth. This avoids the use of the SPWM wave or the dimming switch circuit in the prior art, and the stroboscopic phenomenon due to the discontinuity of the driving current.

A lighting fixture for powering multiple LED groups to generate a selectable color temperature. The lighting fixture provides varying amounts of power to each group of LEDs to achieve a selected color temperature. Current from a driver may be divided between the LED groups based on a selected operational state, which is selected using a switch or other configurable input. The operational states may turn the LED groups on or off or may control an amount of current received by the LED groups. In some configurations, all of the LED groups are always at least partially powered.

An LED lamp arrangement is disclosed to replace a fluorescent lamp in a luminaire with a ballast. The LED lamp arrangement has a rectifier, LEDs, a LED driver, an impedance balance circuit, a line-voltage controller. The rectifier has two inputs connected to the ballast to provide a rectified power line and a ground power line. The LEDs and a LED driver are connected in series between the rectified power line and the ground power line, and the LED driver regulates a LED driving current through the LEDs. The impedance balance circuit is coupled between the inputs. The line-voltage controller controls the impedance balance circuit in response to a line voltage at the rectified power line, so as to tune an impedance between the inputs and make the line voltage approach to a predetermined target voltage.

The present disclosure relates to a fail-safe LED system including an LED circuit arrangement. The LED circuit arrangement includes a plurality of LED strings arranged in parallel with respect to each other. The LED circuit arrangement is supplied with electrical current from a constant current power supply. The fail-safe LED system includes structure for detecting a in at least one of the LED strings a failure that causes increased current to pass through remaining operational LED strings of the plurality of LED strings. The fail-safe LED system also includes a current correction string arranged in parallel with respect to the plurality of LED strings. When activated in response to the detection of a failure, the current correction string accommodates current from the constant current power supply such that the current passing through each operational LED string is reduced to a corrected current level.

A device for driving several light sources is provided, wherein the several light sources are arranged in a matrix structure; wherein the several light sources of the matrix structure are connected to a semiconductor device; wherein a portion of the semiconductor device corresponds to a light source of the matrix structure, wherein the portion of the semiconductor device comprises a diagnosis function which when activated is arranged for supplying an output diagnosis signal.

The invention relates to an optoelectronic circuit (20) intended to receive, between a first node (A.sub.1) and a second node (A.sub.2), a variable voltage (V.sub.RECT), the optoelectronic circuit including: a plurality of light-emitting diodes (D.sub.i) series-assembled between the first node and a third node; a first current limitation/regulation circuit (14) assembled between the third node and the second node; a switching circuit (16) coupling the third node to at least certain light-emitting diodes of the plurality of light-emitting diodes; a capacitor (Cap) including first and second plates; a first diode (D.sub.0D) having its cathode connected to the second plate and having its anode coupled to the second node; and a second diode (D.sub.0C) having its anode connected to the second plate and having its cathode coupled to the third node or to a second current limitation/regulation circuit (38).

In a light source, a plurality of parallel LED strings or columns (R, G, B) share the same current source (12) as a function of time. Current distribution to the LED strings is carried out with semiconductor switches (Q1, Q2, Q3) that are connected in series with the LED strings. Each semiconductor switch and the corresponding LED string is controlled with a dedicated pulse-width modulated colour control signal (C1, C2, C3). The pulse-width modulated control signals control the semiconductor switches (Q1, Q2, Q3) and the LED strings (R, G, B) sequentially active one at a time and to take current from the common current source (12) for the time defined by the corresponding pulse-width modulated control signal (C1, C2, C3). This control establishes colour tone and colour temperature adjustment, which is independent of the operation of the shared current source. The adjustment of the colour tone or colour temperature of a light source may be controlled by two pulse-width modulated colour signals (A, B) from which, in the LED light source, the required number of pulse-width modulated colour control signals (C1, C2, C3) are formed by logical operations, such as NOR, XOR, and AND operations.