Abstract: A lighting device includes a light source that emits an illumination light. The light source includes a first group of light emitting diodes (LEDs) to emit a first light, a second group of LEDs to emit a second light, and a third group of LEDs to emit a third light. The second light is warmer light than the first light, and the third light is cooler light than the first light. The lighting device further includes a first difference amplifier that controls a first current flow through the second group of LEDs at least based on a magnitude of a current flowing through the light source. The lighting device also includes a second difference amplifier that controls a second current flow through the third group of LEDs at least based on the magnitude of the current flowing through the light source.

Abstract: A lighting device include a first string of light emitting diodes (LEDs) to emit a white light having a warm white Correlated Color Temperature (CCT) and a second string of LEDs. The second string of LEDs includes blue light LEDs that emit a blue light and green light LEDs that emit a green light. The lighting device further includes a tuning circuit to adjust an amount of current flowing through the second string of LEDs. The warm white light, the blue light and the green light produce a combined light, and a CCT of the combined light is tuned by adjusting the amount of current flowing through the second string of LEDs.

Abstract: A lighting device includes a first group of light emitting diodes (LEDs) that are in series with each other and that emit a first light having a first correlated color temperature (CCT). The lighting device further includes a second group of LEDs that are in series with each other and that emit a second light having a second CCT. The lighting device also includes an active electrical component in series with the second group of LEDs. The lighting device further includes a switch coupled in series with the second group of LEDs and the electrical component. The first group of LEDs is in a parallel configuration with the switch, the second group of LEDs, and the electrical component.

Abstract: A lighting device includes a ferroresonant transformer that receives an alternating current (AC) power signal and outputs an output power signal. The lighting device further includes a rectifier coupled to the ferroresonant transformer. The rectifier rectifies the output power signal from the ferroresonant transformer and generates a rectified power signal. The lighting device also includes a dc-to-dc converter coupled to the rectifier, wherein the dc-to-dc converter receives the rectified power signal and generates a regulated power signal.

Abstract: A lighting device includes a light source that emits an illumination light. The light source includes a first group of light emitting diodes (LEDs) that emits a first light and a second group of LEDs that emits a second light. The first light has a first Correlated Color Temperature (CCT), and the second light causes the illumination light to have a warmer CCT. The lighting device further includes a differential amplifier to adjust a current flow through the second group of LEDs. The second light is switched on when a current provided to the light source is below a threshold corresponding to the adjustable reference voltage. The lighting device also includes a current sensor to provide a sensor output signal to a second input of the differential amplifier, the sensor output signal having a second voltage corresponding to the current provided to the light source.