A digital power supply system including a microcontroller, a driver, a step down circuit, and a buck and boost circuit is disclosed. The microcontroller circuit provides a first and second plurality of pulse width modulated signals and receives signals indicative of an input current, input voltage, output current, output voltage, and a 3.3 volt supply. The driver receives the first plurality of pulse width modulated signals and a 12 volt supply and provides a DC power signal and the signal indicative of the output current. The step down circuit receives a positive input voltage and provides the 3.3 volt supply. The boost circuit receives the 3.3 volt supply and provides the 12 volt supply. The buck and boost circuit receives the second plurality of pulse width modulated signals and provide the signals indicative of the output voltage, the input current, the input voltage, and the positive input voltage.

A lighting system (1) has a first lighting circuit (2) configured to provide a first predetermined level of lighting intensity. The first lighting circuit (2) is configured to receive power from a mains electricity supply (3) or from a battery source (4) if the mains supply is unavailable. The first lighting circuit (2) is connected to at least one first Light source (5) and configured, when actuated, to provide lighting at the first predetermined level of lighting intensity. At this time, the first light source is in either an on or off state or a level of light required to raise ambient light level above a predetermined level. The system (1) further has a second lighting circuit (13) configured to provide lighting at least a second predetermined level of lighting intensity. The second lighting circuit (13) is configured to receive power from the mains electricity supply (3) and is connected to at least one second light source (14). The second lighting circuit (13) has at least one sensor (18) with an input such that actuation thereof causes the second light source (14) to provide the second predetermined level of lighting intensity for a predetermined period of time, in response to ambient illumination meeting or exceeding a predetermined intensity, when said sensor has no input or has had no input for a predetermined period of time, or until re-set. In the system (1), the second predetermined level of lighting intensity is greater than said first predetermined level of lighting.

A circuit arrangement comprises a first terminal for connection to a voltage source, a second terminal for connection to a first current sink and a third terminal for supplying a potential signal. A first diode string can be connected to the voltage source on the anode side and to the first current sink on the cathode side. The third terminal can be coupled to the cathode side of the first diode string by a resistor. An adjustable reference current sink is coupled to the third terminal, for generating a reference current, and comparison unit coupled to the third terminal on the input side for providing a short-circuit detection signal in dependence on a difference between the potential signal and an adjustable reference voltage. The potential signal can be supplied in dependence on a first short-circuit voltage across the first diode string and in dependence on the reference current.

A pixel driving circuit includes a light-emitting working unit, a driving unit, a data signal input, a initial voltage input, a driving power input and a plurality of control level inputs. The driving unit includes a voltage storage element and a driving element. The driving element includes a first electrode, a second electrode and a control terminal. One end of the voltage storage element is connected to the control terminal of the driving element. The first electrode of the driving element forms a first input port of the input port of the driving unit. The pixel circuit is capable of improving the display effect and improving the display life of AM-OLED.

An LED lighting device using a ballast may be provided that includes: an LED unit which includes at least one LED device; a rectifier which rectifies a current power signal output from the ballast; and a current driving unit which receives an output current of the rectifier and controls the power which is transmitted from the ballast to the LED unit. The current driving unit transmits current which has a magnitude greater than that of the output current of the rectifier to the LED unit.

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.

An improved power converter is disclosed.

A DC-DC converter has a pulse width control circuit producing a sequence of pulses, with an on time, an off time and a switching frequency. The on time as well as the switching frequency are both varied in dependence on a dimming setting.

A driving circuit includes a control circuit and a boost converter circuit. The control circuit receives a sense voltage associated with a direct-current (DC) source voltage, and generates a control signal with a duty cycle that varies with the sense voltage in a monotonically increasing manner. The boost converter circuit receives the DC source voltage and the control signal, thereby providing a driving current for driving light emission of a light emitting component. The driving current has a magnitude positively correlated to the duty cycle of the control signal.

A dimmer system comprising a dimmer having an input interface arranged to receive at least one input for dimming and an output interface for transmitting processed dimming input to at least one LED driver; wherein each of the at least one LED driver is operable to drive a plurality of high powered LED lamp units.