A light emitting diode (LED) running light comprises a current sink and a plurality of series coupled LED block cells; each of the plurality of LED block cells comprising a LED and a bypass circuit to the current sink, wherein each series coupled LED sequentially turns on (lights) when a voltage source increases by additive voltage increments of at least the turn-on voltage of each LED in the series coupled string until all LEDs are on (lit). The current sink maintains a desired current value through the LEDs and may also be used to provide waveforms for diagnostic and timing purposes.

A vehicle lamp comprises a light source, a drive circuit, a CPU, and a gradual varying controller. The drive circuit supplies a driving current to a light source according to a dimming signal. The CPU generates a turn on or off ordering signal that instructs the light source to be turned on or off according to an instruction from a vehicle and information that indicates a driving situation. The gradual varying controller generates the dimming signal that varies gradually with time in response to the turn on or off ordering signal. The vehicle lamp can be switched between a first mode in which the light source is turned off momentarily and a second mode in which the light source is turned off gradually.

An LED driver circuit controls the currents through a plurality of strings of light-emitting diodes (LEDs), which are connected in series. Each LED string has an associated current regulator. The LED strings are connected between the voltage rail and a reference rail on the output of an AC-to-DC rectifier to receive an unfiltered rectified DC voltage. A first current regulator is active during a first voltage range of the DC voltage to provide a current of a first magnitude to a first LED string only. A second current regulator is active during a second voltage range to provide a current of a second magnitude to the first LED string and to a second LED string. A third current regulator is active during a third voltage range to provide a current of a third magnitude to the first LED string, to the second LED string and to a third LED string.

A method of controlling a dimmable light emitting diode (LED) system includes defining two or more dimming regions having respective dimming levels applied to one or more strings of LEDs, continuously supplying a current to the one or more strings of LEDs in a first dimming region, and maintaining an average peak value of the current substantially the same and adjusting a duty cycle of a pulse width modulation (PWM) control signal in a second dimming region to supply the current according to the PWM control signal.

A controllable driver (1) is provided for driving a load. The controllable driver (1) comprises a primary converter (11) and a control circuit (13) isolated from one another by an opto-isolator (18). The controllable driver (11) is isolated from an output load (19) by a magnetically coupled pair of windings (112, 114); wherein said windings are adapted to provide a voltage supply to said output load. A feedback signal from the output load, indicative of a load current flowing in the second winding, is provided to the control circuit by a winding (12) isolated from the first and second windings (112, 114), such that the control circuit (13) remains isolated from the output load. The control circuit also directly receive input control signal without an opto-isolator. The control circuit is also isolated from the switching core (111) of the primary converter (11) via an opto-isolator. Such a controllable driver reduces the likelihood and impact of electromagnetic interference test failures and potential energy surges.

A light emitting diode (LED) control circuit includes an inductor current sense circuit with a high-side diode string, a low-side diode string, and a sense resistor in series with and between the high-side and low side diode strings. The LED control circuit receives an input voltage on an end that connects to the high-side diode string. An end of the low-side diode string is connected to a switch through an inductor. A sense voltage developed on the sense resistor by an inductor current is sensed by a controller integrated circuit (IC). A pin of the controller IC that receives the sense voltage can have a breakdown voltage specification that is lower than the input voltage.

A circuit comprises an amplifier and a plurality of channels, the plurality of channels including respective transistors. The respective transistors of the channels control respective magnitudes of respective currents of the channels according to an output of the amplifier. The respective transistors of the plurality of channels may be included in an auto-commutated circuit. A first Light Emitting Diode (LED) circuit may be coupled between a power source and a first channel of the plurality of channels. A second LED circuit may be coupled between the first channel and a second channel of the plurality of LED channels. The power source may provide rectified Alternating Current (AC).

A thyristor regulation circuit for a high-voltage light-emitting diode (LED) strip light includes: a live wire input terminal, a neutral wire input terminal, a full-bridge rectifier module, a first group of LED circuit modules, a second group of LED circuit modules, a third group of LED circuit modules, a first thyristor chip, a second thyristor chip and a third thyristor chip. The LED strip light includes a plurality of minimum LED strip light units, the minimum LED strip light units are arranged in parallel, and each of the minimum LED strip light units includes the thyristor regulation circuit for a high-voltage LED strip light. In the thyristor regulation circuit, an external bulky power supply is omitted, and an LED strip light is directly connected to the mains electricity for use, thereby reducing the installation difficulty; and the present disclosure is compatible with existing thyristor dimming circuits.

A LED driving device is provided, which includes a LED string including at least one LED element, at least one channel connected to the at least one LED element, a current regulator configured to regulate a current flowing through the at least one channel according to at least one corresponding control voltage, and a control signal generating circuit configured to generate a control signal based on a difference between a reference voltage and a comparative voltage. The comparative voltage is determined based on a sensing voltage, and the sensing voltage corresponds to an LED current flowing through the LED string. The control signal generating circuit is further configured to generate the at least one corresponding control voltage based on the control signal.

A dimmable solid state lighting apparatus can include a plurality of light emitting diode (LED) segments including a first LED segment that can have a targeted spectral power distribution for light emitted from the apparatus that is different than spectral power distributions for other LED segments included in the plurality of LED segments. An LED segment selection circuit can be configured to selectively control current through the plurality of LED segments to shift the light emitted by the apparatus to the targeted spectral power distribution responsive to dimming input.