The invention relates to a device for operating LEDs, comprising a driver module and an LED module (11), which is controlled by the driver module (10) and has at least one LED. The LED module (11) is fed a current by the driver module (10) via a first connection (1), and a second connection (2) is present, preferably as a ground connection (GND). The device is characterized in that the LED module (11) is connected to the driver module (10) by means of a third connection (3), which is designed as a data channel, a voltage fed by the driver module (10) being applied to the data channel.

Methods and systems for controlling current provided to one or more LEDs for a period of time after power supplied to the LED driver is shut down are described herein. By controlling current through the one or more LEDs after shutdown, the light emitted from the one or more LEDs transitions to zero at a predictable rate with a predictable lag time. An LED based illumination system includes an energy storage element and a controlled luminous drawdown module electrically coupled between one or more LEDs and an electrical power converter employed to control current provided to the one or more LEDs during normal operation. The controlled luminous drawdown module senses a reduction in voltage at the output of the electrical power converter and operates to control current flow through one or more LEDs of the LED string until electrical energy stored in the electrical storage element is depleted.

Methods and systems for controlling current provided to one or more LEDs for a period of time after power supplied to the LED driver is shut down are described herein. By controlling current through the one or more LEDs after shutdown, the light emitted from the one or more LEDs transitions to zero at a predictable rate with a predictable lag time. An LED based illumination system includes an energy storage element and a controlled luminous drawdown module electrically coupled between one or more LEDs and an electrical power converter employed to control current provided to the one or more LEDs during normal operation. The controlled luminous drawdown module senses a reduction in voltage at the output of the electrical power converter and operates to control current flow through one or more LEDs of the LED string until electrical energy stored in the electrical storage element is depleted.

An LED power supply (100) configured to detect a characteristic of an input signal, includes a Buck power factor control circuit (D1, U1, Q1, D2, L1, C1) being configured to receive an input signal, the input signal (VAC) being referenced to a power ground, and to output an output signal, the output signal (V.sub.out) being referenced to an output ground, wherein the output ground is level shifted with respect to the power ground; and a controller (106) configured to output an LED drive signal, the controller referenced to the output ground, wherein the controller is configured to determine the characteristic of the input signal according to a switching time of the Buck power factor control circuit, the switching time of the Buck power factor control circuit being determined by the controller according to a switching signal referenced to the output ground.

An LED power supply (100) configured to detect a characteristic of an input signal, includes a Buck power factor control circuit (D1, U1, Q1, D2, L1, C1) being configured to receive an input signal, the input signal (VAC) being referenced to a power ground, and to output an output signal, the output signal (V.sub.out) being referenced to an output ground, wherein the output ground is level shifted with respect to the power ground; and a controller (106) configured to output an LED drive signal, the controller referenced to the output ground, wherein the controller is configured to determine the characteristic of the input signal according to a switching time of the Buck power factor control circuit, the switching time of the Buck power factor control circuit being determined by the controller according to a switching signal referenced to the output ground.

Circuits and methods for driving an LED from a secondary side of a transformer are disclosed herein. An embodiment of the method includes monitoring an input voltage to determine the power level intended to drive the LED. The current flow through the primary side of the transformer is adjusted to make the power actually driving the LED equal to the power intended to drive the LED.

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.

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 post mounted lamp includes: a lamp post; one or more light emitting diode (LED) devices disposed proximate to the top of the lamp post; a power factor (PF) correction circuit disposed proximate to the bottom of the lamp post; wires disposed in the lamp post to deliver PF corrected electrical power from the PF correction circuit to the one or more LED devices; and circuitry disposed proximate to the top of the lamp post to operate the one or more LED devices using the PF corrected electrical power.

Methods for controlling power consumption and 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. The instruction or set of instructions are processed to derive an indication of power consumption for each of the one or more sets of LED light engines. Power allocations for the one or more sets of LED light engines are adjusted to meet targets. This can be done by, e.g., ramping up or down the duty cycle of active sets of LED light engines by a uniform factor until the targets are met. Temperature control methods similarly ramp down the duty cycle of active sets of LED light engines uniformly over time if the measured temperature of the PCB exceeds limits.