A display apparatus with a power supply circuit is provided. The power supply circuit is connected with a light emitting diode (LED) drive circuit, a filter circuit and a feedback circuit in the display apparatus. The power supply circuit includes a fixed-voltage power supply element and a variable-voltage power supply element, and the fixed-voltage power supply element is superposed on the variable-voltage power supply element and configured to supply power to the LED drive circuit in a stepped manner; and a controller is configured to control a voltage of the variable-voltage power supply element according to a variation of the output voltage feedback from the feedback circuit.

A display apparatus with a power supply circuit is provided. The power supply circuit is connected with a light emitting diode (LED) drive circuit, a filter circuit and a feedback circuit in the display apparatus. The power supply circuit includes a fixed-voltage power supply element and a variable-voltage power supply element, and the fixed-voltage power supply element is superposed on the variable-voltage power supply element and configured to supply power to the LED drive circuit in a stepped manner; and a controller is configured to control a voltage of the variable-voltage power supply element according to a variation of the output voltage feedback from the feedback circuit.

According to some embodiments, there is provided a power supply system including a converter configured to generate an output signal based on a rectified input signal for driving a light source, an output correction circuit coupled to an output of the converter and configured to measure a ripple in the output signal and to generate a correction signal to dynamically control a DC-level of the output signal of the converter based on the measured ripple and a reference signal corresponding to a desired DC-level of the output signal.

According to some embodiments, there is provided a power supply system including a converter configured to generate an output signal based on a rectified input signal for driving a light source, an output correction circuit coupled to an output of the converter and configured to measure a ripple in the output signal and to generate a correction signal to dynamically control a DC-level of the output signal of the converter based on the measured ripple and a reference signal corresponding to a desired DC-level of the output signal.

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.

A buffer circuit for an LED driver circuit, a LED driver circuit, and a control method, the buffer circuit includes a first control switch connected in series in a rectified input loop and a feedback control module connected to the rectified input loop to obtain a loop current in the rectified input loop for generating a first control signal to the first control switch according to the loop current and a reference signal. The first control switch switches between a fully conducting state and a non-fully-conducting state based on the first control signal and restrains the loop current when the first control switch is in the non-fully-conducting state. The buffer circuit enhances the effect of restraining the current change rate and can effectively restrain current spikes in a circuit, resulting in higher safety and reliability.

A noise reduction circuit for a matrix LED driver includes a pseudo random number generator, an up counter, a clock module, and a plurality of matrix switch controllers. The matrix switch controllers and the up counter randomly change a power-on sequence applied across matrix switches in the matrix LED driver according to working random numbers generated by the pseudo random number generator. The circuit prevents jitter-induced noise from periodically reoccurring at the power source of the matrix LED driver, thereby reducing noise energy.

A noise reduction circuit for a matrix LED driver includes a pseudo random number generator, an up counter, a clock module, and a plurality of matrix switch controllers. The matrix switch controllers and the up counter randomly change a power-on sequence applied across matrix switches in the matrix LED driver according to working random numbers generated by the pseudo random number generator. The circuit prevents jitter-induced noise from periodically reoccurring at the power source of the matrix LED driver, thereby reducing noise energy.

The present disclosure provides a leakage protection circuit, a method and a drive device. The leakage protection circuit is used for being electrically connected with the power supply line of a load, and may be configured to sample the power supply line at intervals, detect the voltage of the sampled electrical signals to determine whether the voltage of the AC input power is divided, and provide leakage protection based on the determined result. The present disclosure can prevent human from electric shock through sampling the electric signals from the power supply line at intervals and performing voltage detection and comparasion to determine whether the voltage of the accessed AC input power is divided, when the voltage of the accessed AC input power is determined to be divided, the power supply line will be controlled in non-conductive state.

A light-emitting diode (LED) tube lamp and an electric leakage protection circuit are provided. The LED tube lamp. The LED tube lamp includes a leakage detecting module and a driving module comprising a Type A+B driving circuit. The leakage detecting module is connected with a power supply. The driving module is electrically connected with the leakage detecting module. The leakage detecting module detects a signal related to the output current of the power supply, and when the signal related to the output current of the power supply exceeds a reference signal, the leakage detecting module limits the current on a power loop connected to the power supply by periodically turning off a switch electrically connected to the power loop in series.