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.

Methods for controlling temperature in an LED luminaire are disclosed. The LED luminaire has one or more sets of LED light engines disposed on a printed circuit board (PCB), some or all of which are activated in response to an instruction or set of instructions. A temperature of the PCB is measured in at least one location. If the temperature exceeds a threshold, the duty cycle of active sets of LED light engines is ramped down uniformly over time.

The disclosed devices may include a driver circuit including a voltage boost circuit, a pulse modulation controller, and optionally a headroom processor. The voltage boost circuit may be configured to receive a device input voltage (such as a battery voltage) and generate a backlight drive voltage. The pulse modulation controller may be configured to provide a pulse modulation signal to the voltage boost circuit, and may include a digital circuit or an analog circuit. Example devices may include a backlight unit receiving the backlight voltage. The optional headroom processor may provide a headroom signal to the pulse modulation controller based on a headroom voltage determined from the backlight unit. Devices may further include a backlight unit including an arrangement of light-emissive elements, and may include display devices such as head-mounted devices. Various other methods, systems, and computer-readable media are also disclosed.

Method of controlling warning lights to enter low power mode includes steps of: setting predetermined ID Number of warning lights as starter, and remaining ID numbers as receivers; warning light set as starter receiving start command from control bus through signal line, and sending data, clock pulse, and ID information from data bus, and choosing low power mode to flash; warning lights set as receivers obtaining data, clock pulse, and ID information from data bus through signal lines, and flash mode of receivers and starter flashing in low power mode, and active switch of control circuit that executes low power mode receiving low power command sent from starter and forming conductive state, and current-reducing resistor which is electrically connected to active switch reducing passing current to predetermined ratio, so that reduced current is transmitted to receivers and then starter executes low power mode and reduces brightness of warning lights.

Method of controlling warning lights to enter low power mode includes steps of: setting predetermined ID Number of warning lights as starter, and remaining ID numbers as receivers; warning light set as starter receiving start command from control bus through signal line, and sending data, clock pulse, and ID information from data bus, and choosing low power mode to flash; warning lights set as receivers obtaining data, clock pulse, and ID information from data bus through signal lines, and flash mode of receivers and starter flashing in low power mode, and active switch of control circuit that executes low power mode receiving low power command sent from starter and forming conductive state, and current-reducing resistor which is electrically connected to active switch reducing passing current to predetermined ratio, so that reduced current is transmitted to receivers and then starter executes low power mode and reduces brightness of warning lights.

A mini LED television control system and method to reduce loss includes a power supply used for supplying power to a backlight board after a voltage is adjusted; a control board connected to the power supply, the control board including an FPGA used for detecting a current value and controlling a power supply output voltage, an analog-to-digital conversion chip used for collecting the voltages of sampling circuits, and a plurality of sampling circuits connected to a plurality of light boards and used for collecting voltages of the light boards; constant current ICs disposed on the light boards and used for providing light bar voltages and sending brightness information; and a mainboard connected to the control board and used for enabling and synchronizing backlight brightness signals. The control board converts brightness information sent by the mainboard and then sends the information to the constant current ICs on corresponding light boards.

A feedback control circuit in an LED driving circuit for driving a plurality of LED strings. Each LED string provides a headroom detecting voltage. The feedback control circuit has a status detecting circuit, a counting circuit and a modulating circuit. The status detecting circuit compares each headroom detecting voltage with a low headroom threshold voltage and a high headroom threshold voltage and generates an up self-status signal and a down self-status signal. The counting circuit counts or keeps unchanged and then generates a counting signal based on the up self-status signal and the down self-status signal. The modulating circuit generates a modulating signal based on the counting signal. And based on the modulating signal, the feedback control circuit generates a feedback control signal to regulate a bias voltage supplying the plurality of LED strings.

A power supply system includes a converter configured to generate a drive signal based on a rectified input signal for powering a light source, a ripple control system including a voltage-controlled resistor (VCR) coupled to a secondary-side of the converter and configured to dynamically adjust a resistance of the VCR to compensate for ripples in the drive signal, and a controller configured to sense an output voltage of the converter, to calculate a voltage drop across the VCR, and to generate a feedback signal to control the drive signal of the converter based on the sensed output voltage and the calculated voltage drop.

A drive circuit for an LED luminaire is disclosed. The drive circuit includes one or several series of LED light engines. A voltage source with a regulator is connected to the series of LED light engines to forward-bias the light engines. The circuit also includes an integrated circuit driver, which may drive the series of LED light engines using, e.g., pulse-width modulation (PWM). The circuit also includes a feedback circuit connected to the cathode end of the series of LED light engines. The feedback circuit receives a remainder voltage and creates a feedback output signal that upregulates or downregulates the regulator of the voltage source to keep a minimum operating voltage on the integrated circuit driver and also to compensate for variations in forward voltages among LED light engines in the series. A switching element, such as a bipolar junction transistor, protects the driver from high voltages.

A lighting circuit turns on a plurality of semiconductor light sources. Multiple current sources are each coupled to a corresponding semiconductor light source. A switching converter supplies a driving voltage V.sub.OUT across each of multiple series connection circuits each formed of the semiconductor light source and the current source. A converter controller employing a ripple control method turns on a switching transistor of the switching converter in response to a voltage across any one of the multiple current sources decreasing to a bottom limit voltage.