A two-stage driver supplies current to a light emitting diode (LED) load. The driver includes a first stage and a second stage. The second stage is configured to generate a desired current through the LED load. The second stage has a flyback converter having a flyback transformer with a primary winding and a secondary winding. The primary winding is turned on and off by a gating signal. An induced voltage in the secondary winding rings when a current in the secondary winding is discharged. The flyback converter is configured to turn on the primary winding only during a detected valley in the ringing of the secondary winding. If the primary winding is turned on during a detected valley different from the previous detected valley, a valley jump is detected and the switching frequency is adjusted.

A method of driving a light source by a light driver includes measuring a current output signal of the light driver, calculating a percent change in output signal, determining whether the percent change in output signal is greater than or equal to a first threshold, and in response to determining that the percent change in the output signal is greater than or equal to the first threshold, calculating a percent change in reference voltage based on a current reference voltage and a previous reference voltage, determining whether the percent change in reference voltage is less than a second threshold, and in response to determining that the percent change in reference voltage is less than the second threshold, deactivating filtering and averaging of a dimmer signal received from a dimmer for a period of time, and reactivating the filtering and the averaging of the dimmer signal.

A 2-Wire LED dimming system and method re-purposes existing 120V AC architecture and hardware to carry low voltage PWM gradient DC power to the LED lamps provides a consistent gradation over a 0-100% dimming range. An LED Driver is electrically connected to an AC power source and connect to at least one LED lamp. The AC power source is electrically connected to an AC to DC converter where the AC power is converted to filtered and regulated DC power for the control unit and the power switch. The power switch is electrically connected to the AC to DC converter DC power output. The control unit is electrically connected to the power switch which is turned ON or OFF according to the pulse width modulation PWM signal from the control unit in order to connect or disconnect the DC power from the AC to DC converter.

An LED arrangement having a LED string and a smoothing capacitor connected in parallel. A controllable voltage limiter is able to limit a voltage across the LED string to selectively prevent the LED string from outputting light. As the LED arrangement is turned ON, the controllable voltage limiter may activate so that the smoothing capacitor can be charged with a high current without activating the LED string.

An LED arrangement having a LED string and a smoothing capacitor connected in parallel. A controllable voltage limiter is able to limit a voltage across the LED string to selectively prevent the LED string from outputting light. As the LED arrangement is turned ON, the controllable voltage limiter may activate so that the smoothing capacitor can be charged with a high current without activating the LED string.

An LED tube lamp with overvoltage protection capability is provided. The LED tube lamp includes a lamp tube, two external connection terminals, a rectifying circuit, a filtering circuit, an LED module, and a protection circuit. The protection circuit is coupled between two input terminals of the LED module and configured to perform overvoltage protection when determining that a voltage level between the two input terminals of the LED module reaches or is higher than a predefined voltage value, wherein the protection circuit includes a diode and the predefined voltage value is in a range of about 40V to about 600V.

A light-emitting diode (LED) tube lamp comprising a tube, end caps with contact pins and located on both ends of the tube, a first rectifying circuit and a second rectifying circuit and a filtering circuit that are coupled with the contact pins on the two end caps respectively, and a switch circuitry that is located between the rectifying circuits and the filtering circuit characterized in that the switch circuitry is capable of detecting whether the LED tube lamp is correctly installed on a lamp socket so as to reduce the risk of electric shock.

An apparatus for powering a light-emitting diode (LED) is provided including: a circuit board having an input portion, a power portion, a protection portion, and an output portion; the input portion of the circuit board including an alternating current line and a neutral current line, where the alternating current received across the alternating current line and neutral line supply two distinct, alternative paths, where each of the two distinct alternative paths include a combination of capacitors, inductors, and rectifiers to mitigate signal noise; the power portion of the circuit configured to receive power from the input portion of the circuit along the two distinct, alternative paths, to regulate the current received from the two distinct, alternative paths, and to provide power to an LED driver; and the protection portion of the circuit may be configured to mitigate voltage surges and to regulate the voltage supplied to the LED driver.

A flicker measurement method is described. The flicker measurement method includes: providing an electrical measurement device, wherein the electrical measurement device includes at least one signal input; providing an LED driver, wherein the LED driver is configured to generate a power signal; electrically connecting the LED driver with the at least one signal input; generating a power signal by the LED driver; and determining a flicker metric based on the power signal by the electrical measurement device. Further, a flicker measurement system is described.

An LED lamp and it power source module are provided. The LED lamp includes an LED module and a power source module. The power source module includes two rectifying circuits, a filtering capacitor, a plurality of fuses, two filament-simulating circuits, and a discharge device. Each of the filament-simulating circuits is configured to allow a current to flow from one pin to the other pin via the corresponding first and second filament-simulating circuits during a pre-heat process executed by a ballast.