An LED lighting apparatus includes a first LED light source and a second LED light source included in a first light source group; a third LED light source and a fourth LED light source included in a second light source group; a mode detection circuit configured to determine a mode; a current control unit for serial and parallel connection of the first light source group and the second light source group; balancing circuits for serial and parallel connection of the respective light source groups; and a current path providing circuit for providing current paths. The LED lighting apparatus performs light emission in various states depending on the change of a rectified voltage and the change of a mode.

A circuit may be configured to deliver current to one or more light emitting diodes (LEDs). The circuit may comprise a first current path configured to deliver a first current to the one or more LEDs, and a second current path in parallel with the first current path, wherein the second current path is configured to deliver a second current through a voltage drop element and to the one or more LEDs. According to this disclosure, a sum of the first current and the second current is regulated based on a sensed current through the circuit.

A circuit may be configured to deliver current to one or more light emitting diodes (LEDs). The circuit may comprise a first current path configured to deliver a first current to the one or more LEDs, and a second current path in parallel with the first current path, wherein the second current path is configured to deliver a second current through a voltage drop element and to the one or more LEDs. According to this disclosure, a sum of the first current and the second current is regulated based on a sensed current through the circuit.

A balance circuit includes a reference circuit configured to generate current through strings of light emitting diodes (LEDs). The reference circuit includes a first string of LEDs in series coupled to a collector node of a first transistor. A base drive current resistor is connected between the collector node and a base node of the first transistor. A base emitter resistor is connected between the base node and an emitter of the first transistor such that a reference voltage is generated on the base node during operation. Another stage receives the reference voltage to generate a tracking current through a second transistor and a second string of LEDs connected to a base of the second transistor, wherein a current through the first string of LEDs is uniformly tracked by the tracking current through the second string of LEDs.

A balance circuit includes a reference circuit configured to generate current through strings of light emitting diodes (LEDs). The reference circuit includes a first string of LEDs in series coupled to a collector node of a first transistor. A base drive current resistor is connected between the collector node and a base node of the first transistor. A base emitter resistor is connected between the base node and an emitter of the first transistor such that a reference voltage is generated on the base node during operation. Another stage receives the reference voltage to generate a tracking current through a second transistor and a second string of LEDs connected to a base of the second transistor, wherein a current through the first string of LEDs is uniformly tracked by the tracking current through the second string of LEDs.

An LED lighting assembly (1) comprising a cassette (2), a lens, a printed circuit board, PCB, (6) having at least one LED light source mounted thereon, the lighting assembly comprising an LED driver circuit arranged to maintain conduction in the circuit, the PCB using a first amount of power and wherein the LED driver circuit is arranged to simulate use of a second amount of power, the second amount being lower than the first amount. The LED lighting assembly comprises a capacitor arranged to be activated when a voltage across the LED driver circuit is below a first predetermined level. A resistor or resistor/capacitor combination is connectable to a trickle sensor in a passenger service unit (PSU).

A retrofit lamp is to be used with a ballast. A shunt switch is provided in parallel with an output load and is adapted to shunt input terminals of the lamp using pulse width control so as to tune the current through the lighting element. This current control is used to enable compatibility with different ballasts and to provide dimming control. A detection circuit is used to detect an abnormal drive condition of the retrofit lamp and the pulse width control of the shunt switch can then be overridden by holding the shunt switch at a stable state for a certain duration. This prevents overload conditions and avoids DC signals in the event of component failures.

A lighting device circuit comprising: a reference LED string, a mirror LED string coupled in parallel to the reference LED string, an operational amplifier based current mirror circuit coupled to the reference LED string and to the mirror LED string, and a window comparator circuit that includes only a single input that is coupled to a fault sense node. The fault sense node directly connects to a drain node of a transistor within the operational amplifier based current mirror and a LED within the mirror LED string.

A lighting device circuit comprising: a reference LED string, a mirror LED string coupled in parallel to the reference LED string, an operational amplifier based current mirror circuit coupled to the reference LED string and to the mirror LED string, and a window comparator circuit that includes only a single input that is coupled to a fault sense node. The fault sense node directly connects to a drain node of a transistor within the operational amplifier based current mirror and a LED within the mirror LED string.

A circuit may be configured to deliver current to one or more light emitting diodes (LEDs). The circuit may comprise a first current path configured to deliver a first current to the one or more LEDs, and a second current path in parallel with the first current path, wherein the second current path is configured to deliver a second current through a voltage drop element and to the one or more LEDs. According to this disclosure, a sum of the first current and the second current is regulated based on a sensed current through the circuit.