Abstract: A LED circuit comprises a current drive circuit for driving a current through the parallel combination of a LED arrangement and an output capacitor. An override arrangement overrides the current level setting to a default current level during start-up, and the override arrangement is disabled when a current flow is sensed by a sensor. The current setting of the driver is ignored until a threshold current is sensed through the LED arrangement. The delay associated with initial start-up charging of the output capacitor is thereby avoided.

Abstract: A light source driver for a light source of a luminaire. The disclosure proposes to monitor a parameter, responsive to or a cause of a temperature change in a resistive element to facilitate determination of whether the light source driver is compatible with an AC supply. The resistive element in connected in series between the rectifying arrangement, of the light source driver, and the energy storage capacitor for storing charge that powers the light source.

Abstract: A LED driver circuit uses a first current source circuit to set an output current, controlled by pulse width modulation and a second current source circuit for charging a storage capacitor. A compensating arrangement is used for increasing the current delivered by the second current source circuit during off period times of the pulse width modulation. This compensates the current drawn from the input and enables better timing control of the input current pulses.

Abstract: An LED arrangement having a LED string and a smoothing capacitor connected in parallel. A controllable voltage limiter is able to limit a voltage across the LED string to selectively prevent the LED string from outputting light. As the LED arrangement is turned ON, the controllable voltage limiter may activate so that the smoothing capacitor can be charged with a high current without activating the LED string.

Abstract: A Light Emitting Diode, LED, driver arranged for driving at least one LED, said LED driver comprising a rectifier arranged for receiving an Alternating Current, AC, supply voltage and for providing an output Direct Current, DC, voltage to said at least one LED, a voltage regulating branch arranged for controlling an LED voltage provided to said at least one LED, via a supply line, wherein said voltage regulating branch is arranged for receiving said DC voltage from said rectifier, wherein said voltage regulating branch comprises, a capacitor arranged for providing said LED voltage to said at least one LED, a current limiter, connected in series with said capacitor, and arranged for charging said capacitor thereby providing said LED voltage and a feedback circuit arranged for controlling the charging of said capacitor by said current limiter, and thereby controlling the LED voltage provided to said at least one LED, by regulating a minimum residual headroom voltage present on a LED current limiter coupled in s

Abstract: The invention relates to a lighting system comprising a load comprising a parallel configuration of a first LED load having a first forward voltage, and a first switch coupled in series with the first LED load; and a second LED load, having a second forward voltage being different than the first forward voltage; a switched mode power supply comprising a switching element; an inductor; a diode; a set of output pins for coupling to the load; and a capacitor coupled across the set of output pins; wherein the switched mode power supply is arranged to provide a voltage across the set of output pins, wherein the lighting system comprises a further inductor coupled between the one of the output pins and the load.

Abstract: A light source driver for a light source of a luminaire. The disclosure proposes to monitor a parameter, responsive to or a cause of a temperature change in a resistive element to facilitate determination of whether the light source driver is compatible with an AC supply. The resistive element in connected in series between the rectifying arrangement, of the light source driver, and the energy storage capacitor for storing charge that powers the light source.

Abstract: A lighting arrangement such as a LED lamp comprises a light source and associated current driver, or a set of at least two parallel light sources and associated current drivers, supplied by a DC voltage from a voltage-regulated power converter. A feedback circuit provides a temperature-dependent control input to a control loop of the power converter, such that the DC voltage is adjusted in dependence on a sensed temperature. In this way, the voltage headroom required can be reduced, and efficiency gains are made.

Abstract: An LED arrangement having a LED string and a smoothing capacitor connected in parallel. A controllable voltage limiter is able to limit a voltage across the LED string to selectively prevent the LED string from outputting light. As the LED arrangement is turned ON, the controllable voltage limiter may activate so that the smoothing capacitor can be charged with a high current without activating the LED string.

Abstract: A LED circuit comprises a current drive circuit for driving a current through the parallel combination of a LED arrangement and an output capacitor. An override arrangement overrides the current level setting to a default current level during start-up, and the override arrangement is disabled when a current flow is sensed by a sensor. The current setting of the driver is ignored until a threshold current is sensed through the LED arrangement. The delay associated with initial start-up charging of the output capacitor is thereby avoided.

Abstract: A lighting arrangement such as a LED lamp comprises a light source and associated current driver, or a set of at least two parallel light sources and associated current drivers, supplied by a DC voltage from a voltage-regulated power converter. A feedback circuit provides a temperature-dependent control input to a control loop of the power converter, such that the DC voltage is adjusted in dependence on a sensed temperature. In this way, the voltage headroom required can be reduced, and efficiency gains are made.

Abstract: The invention relates to a lighting system comprising a load comprising a parallel configuration of a first LED load having a first forward voltage, and a first switch coupled in series with the first LED load; and a second LED load, having a second forward voltage being different than the first forward voltage; a switched mode power supply comprising a switching element; an inductor; a diode; a set of output pins for coupling to the load; and a capacitor coupled across the set of output pins; wherein the switched mode power supply is arranged to provide a voltage across the set of output pins, wherein the lighting system comprises a further inductor coupled between the one of the output pins and the load.

Abstract: An LED lighting driver has a switched mode power supply which generates an auxiliary power supply. The auxiliary power supply circuit has a first power supply inductor and a second power supply inductor in series with each other. The second power supply inductor is selectively switched into or out of the auxiliary power supply circuit, thereby varying a transformer ratio to the main energy storage inductor. The switching may be made based on a light output mode or a standby mode being in operation. The standby mode then enables more efficient generation of an auxiliary supply voltage.

Abstract: An LED lighting driver has a switched mode power supply which generates an auxiliary power supply. The auxiliary power supply has a dummy load, and a control circuit for controlling the connection of the dummy load in parallel with the auxiliary load in dependence on the current drawn by the auxiliary load. In this way, a current drawn by the auxiliary load is made more stable so that effects of auxiliary supply fluctuations on the light output are reduced.

Abstract: A lighting circuit makes use of a switch mode power converter to drive a solid state lighting arrangement having a lighting unit and a lighting control switch. A pulse width modulation control signal is applied to the lighting control switch for dimming control with an activation pulse during which the lighting unit is activated. The power converter delivers a triangular current waveform and the activation pulse is delayed until a predetermined point within the triangular current waveform. This ensures that the PWM pulse during which the lighting arrangement is turned on has timing which is synchronized with the timing of the switch mode power converter. The prevents beat frequencies so that visible flicker is avoided.

Abstract: An AC input power converter comprising a rectifier circuit (D3, D4, D5, D6) for rectifying an AC input signal, a first unidirectional device (D1) coupled in series with a first capacitor (C1) for charging the first capacitor (C1) and wherein the first unidirectional device (D1) and the first capacitor (C1) are arranged in parallel to an output of the rectifier circuit (D3, D4, D5, D6), a second unidirectional device (D2) coupled in series with a second capacitor (C2) for charging the second capacitor (C2) and wherein the second unidirectional device (D2) and the second capacitor (C2) are arranged in parallel to an output of the rectifier circuit (D3, D4, D5, D6), a first output (OUT1) for providing a first power and a first average voltage to a first power converter, wherein the first output (OUT1) s coupled to a first node between the first capacitor (C1) and the first unidirectional device (D1) and a second output (OUT2) for providing a second power and a second average voltage to a second power converter,

Abstract: Disclosed is a method and apparatus for overcoming LED flicker caused by an asynchronous control of an LED on or off state and a switched-mode power supply for the LED. A supplementary control system is adapted to override a primary control system for the switched-mode power supply, and control an energy storage inductor of the switched-mode power supply. In particular, in response to an indicated desire to switch the LED on, the supplementary control system sets the current in the energy storage inductor to a predetermined level. In this way, when the LED is switched on, the current through the inductor is known and LED flicker is thereby reduced.

Abstract: An LED lighting driver has a switched mode power supply which generates an auxiliary power supply. The auxiliary power supply has a dummy load, and a control circuit for controlling the connection of the dummy load in parallel with the auxiliary load in dependence on the current drawn by the auxiliary load. In this way, a current drawn by the auxiliary load is made more stable so that effects of auxiliary supply fluctuations on the light output are reduced.

Abstract: An analogue dimmer driver for driving an LED lighting element (54) to generate coded light comprises an output component (54) which provides a primary current (ipr), a capacitor (53) connected to the output component, a switch (S1) via which the lighting element is connectable to the current source in parallel with the capacitor. Switching is performed by periodically opening and closing the switch to code information into light generated by the lighting element. The output component has an input configured to receive a dimming signal. Responsive to a change in the dimming signal: i) the primary current is increased so as to increase the average power of the generated light and ii) the duty cycle of the switching is increased by an amount sufficient to prevent the peak level of the current though the lighting element when the switch is closed (ipr+idis) from exceeding a predetermined level (inom).

Abstract: A lighting circuit makes use of a switch mode power converter to drive a solid state lighting arrangement having a lighting unit and a lighting control switch. A pulse width modulation control signal is applied to the lighting control switch for dimming control with an activation pulse during which the lighting unit is activated. The power converter delivers a triangular current waveform and the activation pulse is delayed until a predetermined point within the triangular current waveform. This ensures that the PWM pulse during which the lighting arrangement is turned on has timing which is synchronized with the timing of the switch mode power converter. The prevents beat frequencies so that visible flicker is avoided.