The invention relates to a power factor correction (PFC) circuit (20), comprising an inductor (21) which is configured to provide a discharge current, a capacitor (23) which is connected to the inductor (21) via a switch (24) and which can be charged with said discharge current, a control unit (14) which is configured to alternately switch the switch (24) on and off based on a feedback control, wherein the control unit (14) has an input interface (42) for receiving a feedback signal (ZXCS) which represents a discharge voltage of the inductor (21), wherein the control unit (14), in a DCM mode, is further configured to calculate a switch on time (T.sub.on) of the switch (24) which is after a first local minimum of the discharge voltage, and wherein, after switching off the switch (24), the control unit is configured to: either switch on the switch (24) at a next or closest local minimum of the inductor voltage after Ton, in case Ton is less than a directly or indirectly set reference time (T.sub.ref), or close the switch (24) at T.sub.on, in case T.sub.on is equal to or exceeds T.sub.ref.

A light-emitting diode (LED) light string control system with carrier identification function includes a control module, a power capacitor, and an LED light string. The control module converts a DC voltage to carry signals on the DC voltage through a power switch according to a lighting command. The power capacitor performs a capacitive charge-discharge operation to the signals on the DC voltage to generate capacitive charge-discharge signals. The LED light string includes at least one LED module, and the at least one LED module identifies that a charge-discharge characteristic is a first logic, a second logic, or a latch indication, and to generate a drive command corresponding to the signals on the DC voltage according to one of the first logic, the second logic, and the latch identification to control lighting behavior of the LED light string.

A light-emitting diode (LED) light string control system with carrier identification function includes a control module, a power capacitor, and an LED light string. The control module converts a DC voltage to carry signals on the DC voltage through a power switch according to a lighting command. The power capacitor performs a capacitive charge-discharge operation to the signals on the DC voltage to generate capacitive charge-discharge signals. The LED light string includes at least one LED module, and the at least one LED module identifies that a charge-discharge characteristic is a first logic, a second logic, or a latch indication, and to generate a drive command corresponding to the signals on the DC voltage according to one of the first logic, the second logic, and the latch identification to control lighting behavior of the LED light string.

A linear regulator (40) supplies a first drive current (I1) to a first light source (24) in a first period in which the first light source (24) is turned on and a second light source (25) is not turned on, and in a second period in which the first light source (24) and the second light source (25) are turned on, and stops the supply of the first drive current (I1) in a third period in which the first light source (24) and the second light source (25) are turned off. A switching regulator (41) supplies a second drive current (I2) to the second light source (25) in the second period, and stops the supply of the second drive current (I2) in the third period.

An LED illumination device for improving anti-surge capability includes a circuit substrate, a bridge rectifier chip, a surge absorber group, a first anti-surge current-limiting chip group, a second anti-surge current-limiting chip group, an LED illuminating group, and an LED current-limiting group. The surge absorber group is disposed on the circuit substrate and electrically connected to the bridge rectifier chip for absorbing a surge voltage. The first anti-surge current-limiting chip group is disposed on the circuit substrate for absorbing a first predetermined surge voltage. The second anti-surge current-limiting chip group is disposed on the circuit substrate for absorbing a second predetermined surge voltage. The LED illuminating group includes a plurality of LED chips disposed on the circuit substrate. The LED current-limiting group is disposed on the circuit substrate for controlling a total harmonic distortion of current (THDi) of the LED illuminating group.

An LED illumination device for improving anti-surge capability includes a circuit substrate, a bridge rectifier chip, a surge absorber group, a first anti-surge current-limiting chip group, a second anti-surge current-limiting chip group, an LED illuminating group, and an LED current-limiting group. The surge absorber group is disposed on the circuit substrate and electrically connected to the bridge rectifier chip for absorbing a surge voltage. The first anti-surge current-limiting chip group is disposed on the circuit substrate for absorbing a first predetermined surge voltage. The second anti-surge current-limiting chip group is disposed on the circuit substrate for absorbing a second predetermined surge voltage. The LED illuminating group includes a plurality of LED chips disposed on the circuit substrate. The LED current-limiting group is disposed on the circuit substrate for controlling a total harmonic distortion of current (THDi) of the LED illuminating group.

A power supply including: an AC input power connector; an AC-DC converter circuit coupled to the AC input power connector; a constant-current constant-voltage control unit configured to receive DC power from the AC-DC converter circuit; a light emitting diode (LED) lamp unit configured to receive power from the constant-current constant-voltage control unit; and a capacitor coupled in parallel with the LED lamp unit.

A lighting device includes a light source emitting light having a first bandwidth. A single optic device is coupled to the light source. The single optic device filters light having a preselected subrange of wavelengths within the first bandwidth to generate a first filtered light. The single optic device controls a shape of a beam of the filtered light. The filtered light creates a high-intensity narrow-spectrum light output. A second light source emits a high-intensity narrow-spectrum light output.

A lighting device includes a light source emitting light having a first bandwidth. A single optic device is coupled to the light source. The single optic device filters light having a preselected subrange of wavelengths within the first bandwidth to generate a first filtered light. The single optic device controls a shape of a beam of the filtered light. The filtered light creates a high-intensity narrow-spectrum light output. A second light source emits a high-intensity narrow-spectrum light output.

A method for controlling an amount of power delivered to an electrical load may include controlling an average magnitude of a load current towards a target load current that ranges from a maximum-rated current to a minimum-rated current in a normal mode, and controlling the average magnitude of the load current below the minimum-rated current in a burst mode. The burst mode may include at least one burst-mode period that comprises a first time period associated with an active state and a second time period associated with an inactive state. During the burst mode, the method may include regulating a peak magnitude of the load current towards the minimum-rated current during the active state, and stopping the generation of at least one drive signal during the inactive state to control the average magnitude of the load current to be less than the minimum-rated current.