A lighting circuit turns on multiple semiconductor light sources. Multiple current sources are each coupled in series with a corresponding one from among the semiconductor light sources. A switching converter supplies a driving voltage V.sub.OUT across each of multiple series connection circuits formed of the multiple semiconductor light sources and the multiple current sources. A converter controller controls a switching transistor of the switching converter based on a relation between a voltage across one from among the multiple current sources and a reference voltage having a positive correlation with the temperature T.sub.j.

A light emitting diode (LED) device is provided. The LED device a first LED string configured to emit light having a first color temperature; a second LED string connected to the first LED string in parallel, and configured to emit light having a second color temperature different from the first color temperature; a controller configured to generate a control signal based on a control command received from an external controller; a switching circuit configured to control brightness of any one or any combination of the first LED string and the second LED string based on the control signal; and a power supply configured to generate an internal power voltage for operation of the controller and the switching circuit.

A light emitting diode (LED) device is provided. The LED device a first LED string configured to emit light having a first color temperature; a second LED string connected to the first LED string in parallel, and configured to emit light having a second color temperature different from the first color temperature; a controller configured to generate a control signal based on a control command received from an external controller; a switching circuit configured to control brightness of any one or any combination of the first LED string and the second LED string based on the control signal; and a power supply configured to generate an internal power voltage for operation of the controller and the switching circuit.

Disclosed are a temperature sampling device and method, a temperature protection device and method, and a lighting system. The temperature sampling device comprises: a temperature measurement unit and a signal processing unit, the temperature measurement unit having a measurement end and configured to change its own resistance under the influence of an ambient temperature change of a circuit to be protected, and the signal processing unit being coupled to the measurement end and configured to limit a measurement signal in the temperature measurement unit that is influenced by a resistance change so as to output a temperature sampling signal corresponding to the resistance change, wherein the temperature sampling signal is generated under the condition that the measurement signal is limited. The temperature sampling device and method, the temperature protection device and method, and the lighting system have simple structure and low costs. In addition, the temperature sampling device can be directly coupled to pins of switch power sources in the existing LED lighting systems, and therefore has high universality.

A lighting fixture includes a fixture housing. A circuit board is positioned in the fixture housing. The circuit board includes a driver circuit. A plurality of light emitters are disposed on the circuit board. The light emitters are operatively connected to the driver circuit to produce a light output. A temperature sensor is disposed on the circuit board, the temperature sensor configured to measure a temperature of the circuit board and output a signal. The driver circuit is configured to reduce the light output in response to the signal from the temperature sensor.

A method and apparatus for an adaptable vehicle light fixture is provided to activate varying light distribution patterns based upon preconfigured operation of trigger and/or power wires. One or more trigger and/or power wires connected to one or more vehicle light fixtures are preconfigured through wired and/or wireless programming to generate specified light distribution patterns that are responsive to the preconfigurations during manual operation. Wireless preconfiguration includes the use of a handheld magnetic device or smartphone. Wired preconfiguration includes the use of a vehicle-based controller area network (CAN) bus. Any preconfigured operation may be changed at any time by the user by programmably changing the preconfiguration.

The current regulation system, providing fine dimming control, has an under-voltage circuit, an over-temperature control circuit, and sometimes a variable resistor (VR) control circuit. The under-voltage and over-temperature controls (first and second control signals) pass through voltage limiters such that the lowest level voltage control signal is applied to the voltage reference signal IREF input of LED IC driver. IC driver has a voltage reference input IREF which controls an IC output current for an LED load demand. The VR control generates a third control signal at the junction to reduce the voltage reference signal under control of the VR. The lowest level control signal dims the LED lamps. Since low level voltage control signals are used, a low voltage turn OFF circuit applies an IC disablement signal to the LED IC driver input control based upon sensing a very low voltage at the junction.

The current regulation system, providing fine dimming control, has an under-voltage circuit, an over-temperature control circuit, and sometimes a variable resistor (VR) control circuit. The under-voltage and over-temperature controls (first and second control signals) pass through voltage limiters such that the lowest level voltage control signal is applied to the voltage reference signal IREF input of LED IC driver. IC driver has a voltage reference input IREF which controls an IC output current for an LED load demand. The VR control generates a third control signal at the junction to reduce the voltage reference signal under control of the VR. The lowest level control signal dims the LED lamps. Since low level voltage control signals are used, a low voltage turn OFF circuit applies an IC disablement signal to the LED IC driver input control based upon sensing a very low voltage at the junction.

An LED driver measures a voltage across the LED and a temperature associated with the LED. The LED driver drives the LED to operate below a knee in the voltage/current curve of the LED and derives an expected voltage across the LED from the temperature of the LED, the LED driving current, and a predetermined relation between the expected LED voltage and at least one of LED temperature and LED driving current. The LED driver determines if the measured voltage across the LED exceeds the expected voltage across the LED, and establishes, based on the determination, if an LED approaching end of life warning is to be generated. Thus, an approaching end of life may be determined by the LED driver while the LED is still operational.

An LED driver measures a voltage across the LED and a temperature associated with the LED. The LED driver drives the LED to operate below a knee in the voltage/current curve of the LED and derives an expected voltage across the LED from the temperature of the LED, the LED driving current, and a predetermined relation between the expected LED voltage and at least one of LED temperature and LED driving current. The LED driver determines if the measured voltage across the LED exceeds the expected voltage across the LED, and establishes, based on the determination, if an LED approaching end of life warning is to be generated. Thus, an approaching end of life may be determined by the LED driver while the LED is still operational.