The present disclosure generally relates to the field of fire alarms. The teachings thereof may be embodied in a strobe notification appliance having: a boost circuit connected to an input voltage; an energy storage circuit charged by the boost circuit; a drive circuit generating a drive current; an LED circuit with at least one LED element; a first sampling circuit collecting an overall voltage drop of all the LED elements; and a control circuit configured to adjust the drive circuit to supply a working current during an alarming stage and supply a detection current during a detection stage. The detection current is lower than the working current and thereby light energy produced by the LED elements during the detection stage is lower than alarming light energy produced during the alarming stage. During the detection stage, the control circuit determines whether the LED circuit works normally based on the collected overall voltage drop.

An LED lighting device having an LED lamp series circuit with a first LED lamp and with a second LED lamp that is coupled to the first LED lamp through a lamp coupling point, an anode, a cathode, driver electronics for connection to the anode and the cathode for operation of the LED lamp series circuit, and a detection device for detecting a failure of the first LED lamp and the second LED lamp. The detection device, together with the first LED lamp and the second LED lamp, forms a first measuring bridge circuit. In addition, the invention relates to a motor vehicle with an LED lighting device according to the invention.

An LED lighting device having an LED lamp series circuit with a first LED lamp and with a second LED lamp that is coupled to the first LED lamp through a lamp coupling point, an anode, a cathode, driver electronics for connection to the anode and the cathode for operation of the LED lamp series circuit, and a detection device for detecting a failure of the first LED lamp and the second LED lamp. The detection device, together with the first LED lamp and the second LED lamp, forms a first measuring bridge circuit. In addition, the invention relates to a motor vehicle with an LED lighting device according to the invention.

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 device includes a plurality of first LEDs, a plurality of second LEDs, at least one controllable current source that is configured to generate at least one bias current for driving the plurality of first LEDs and the plurality of second LEDs, and a plurality of measurement circuits, each of which is configured to measure a current-voltage (I-V) performance characteristic of at least one of the plurality of first LEDs. A property of a first bias current of the at least one bias current is determined as a function of at least two measurements of the I-V performance characteristic of the at least one of the plurality of first LEDs, and the at least two measurements of the I-V performance characteristic are acquired while the first bias current is applied to the at least one of the plurality of first LEDs and the plurality of second LEDs.

A lamp control device comprises a first input terminal, a second input terminal, an output terminal that is configured to be connectable to a lamp via an external switch and outputs a drive current for the lamp, an internal switch provided on a first path connecting the first input terminal and the output terminal, a constant current section provided on a second path connecting the second input terminal and the output terminal, a voltage monitoring section that monitors a voltage applied to the output terminal, and a control section that controls the internal switch on the basis of a monitoring result from the voltage monitoring section.

A lamp control device comprises a first input terminal, a second input terminal, an output terminal that is configured to be connectable to a lamp via an external switch and outputs a drive current for the lamp, an internal switch provided on a first path connecting the first input terminal and the output terminal, a constant current section provided on a second path connecting the second input terminal and the output terminal, a voltage monitoring section that monitors a voltage applied to the output terminal, and a control section that controls the internal switch on the basis of a monitoring result from the voltage monitoring section.

A method, apparatus, and system for operating wide area lighting systems. Operating costs, as well as capital and installation costs, can be reduced by designing the lighting system for operation of individual light sources at a first “normal” operating power for a majority of the time but having the ability to boost or increase operating power for “boosted” or increased light output for the same light sources of the system for a minority of cumulative operating time of the light sources. “”In one aspect, performance data about the LED light sources is evaluated relative to whether or not the light sources will have a predicted life expectancy on the order of the entire lighting system life expectancy. Operating power levels for boosted and normal LED lumen outputs are selected to comport with predictably meeting or exceeding lighting system life expectancy.

An electrical interface module (EIM) is provided between an LED illumination device and a light fixture. The EIM includes an arrangement of contacts that are adapted to be coupled to an LED illumination device and a second arrangement of contacts that are adapted to be coupled to the light fixture and may include a power converter. Additionally, an LED selection module may be included to selectively turn on or off LEDs. A communication port may be included to transmit information associated with the LED illumination device, such as identification, indication of lifetime, flux, etc. The lifetime of the LED illumination device may be measured and communicated, e.g., by an RF signal, IR signal, wired signal or by controlling the light output of the LED illumination device. An optic that is replaceably mounted to the LED illumination device may include, e.g., a flux sensor that is connected to the electrical interface.

A lighting apparatus for a motor vehicle includes a processing module configured to receive, process and send signals from a data bus of the motor vehicle, and a light-emitting diode (LED) unit configured to emit light of adjustable brightness and prescribed color locus. The LED unit has a microcontroller and a plurality of LEDs, where the microcontroller and the LEDs are surrounded by a package of the LED unit. The LED unit is further configured to communicate bidirectionally with the processing module so that a present status value of the LED unit, which status value is representative of a functionality of the LED unit, is ascertainable by the LED unit and the processing module.