A voltage sensing circuit uses a voltage divider for providing a sense signal indicating the voltage across a circuit component. A current injector is used for injecting current to the sensing terminal. A sense signal is obtained with no current injection, to determine if a fault is present. The sensing terminal is coupled to the external circuit component via a voltage clamping component. A further sense signal is obtained in response to the injection of current. By comparing the sense signal in response to the injected current and a clamping voltage of the voltage clamping component, it can then be determined if the fault is caused by the circuit component or by the voltage divider.

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 power converter for an LED lighting device includes a primary side circuit, a secondary side circuit, a detecting circuit, a load-dependent circuit, and a feedback circuit. The feedback circuit generates a feedback signal according to a detected signal which the detecting circuit generates according to a second node of the secondary side circuit. The primary side circuit adjusts a duty cycle according to the feedback signal. The secondary side circuit outputs a first output voltage at a first node of the secondary side circuit and outputs a second output voltage at a third node of the secondary side circuit, according to the duty cycle of the primary side circuit. The load-dependent circuit receives the second output voltage and controls an electrical strength between the first node and the second node of the secondary side circuit according to the first output voltage.

A power converter for an LED lighting device includes a primary side circuit, a secondary side circuit, a detecting circuit, a load-dependent circuit, and a feedback circuit. The feedback circuit generates a feedback signal according to a detected signal which the detecting circuit generates according to a second node of the secondary side circuit. The primary side circuit adjusts a duty cycle according to the feedback signal. The secondary side circuit outputs a first output voltage at a first node of the secondary side circuit and outputs a second output voltage at a third node of the secondary side circuit, according to the duty cycle of the primary side circuit. The load-dependent circuit receives the second output voltage and controls an electrical strength between the first node and the second node of the secondary side circuit according to the first output voltage.

A lighting apparatus includes a light source, a driver circuit, a high side control module and a low side control module. The light source includes a LED module. The driver circuit includes a high side circuit and a low side circuit for generating a driving current to the LED module. The high side control module for controls the high side circuit. The high side control module includes a voltage stabilizer and a current trigger. The voltage stabilizer is placed on a voltage input of a high side. The current trigger is connected to an output of the voltage stabilizer. The low side control module controls the low side circuit. The low side control module includes a buck converter, a constant current trigger, and a low side constant current source. The buck converter is connected to a second input of the current trigger.

A lighting apparatus includes a light source, a driver circuit, a high side control module and a low side control module. The light source includes a LED module. The driver circuit includes a high side circuit and a low side circuit for generating a driving current to the LED module. The high side control module for controls the high side circuit. The high side control module includes a voltage stabilizer and a current trigger. The voltage stabilizer is placed on a voltage input of a high side. The current trigger is connected to an output of the voltage stabilizer. The low side control module controls the low side circuit. The low side control module includes a buck converter, a constant current trigger, and a low side constant current source. The buck converter is connected to a second input of the current trigger.

A light-emitting diode (LED) drive method, an LED drive circuit, and an LED lighting device are disclosed. The method includes: setting preset values of a maximum on-time parameter and a current limit parameter, where the preset values are in at least two sets; selecting a set of the preset values of the maximum on-time parameter and the current limit parameter after a value of a voltage signal on a direct current (DC) bus is detected; controlling a drive current flowing through an LED load based on a selected maximum on-time parameter and a selected current limit parameter. The maximum on-time parameter and the current limit parameter of the system can be adaptively adjusted according to an input voltage, so that the system can have a preferred dimming schedule and dimming depth while realizing a constant current in a wider input voltage range.

A light-emitting diode (LED) drive method, an LED drive circuit, and an LED lighting device are disclosed. The method includes: setting preset values of a maximum on-time parameter and a current limit parameter, where the preset values are in at least two sets; selecting a set of the preset values of the maximum on-time parameter and the current limit parameter after a value of a voltage signal on a direct current (DC) bus is detected; controlling a drive current flowing through an LED load based on a selected maximum on-time parameter and a selected current limit parameter. The maximum on-time parameter and the current limit parameter of the system can be adaptively adjusted according to an input voltage, so that the system can have a preferred dimming schedule and dimming depth while realizing a constant current in a wider input voltage range.

A multi-channel constant current circuit and a lighting device are provided. The multi-channel constant current circuit is used to drive UVC LED to emit light, and includes a constant voltage circuit and a first number of linear constant current diodes. The constant voltage circuit includes a power input terminal, a power output terminal and a voltage regulation sub-circuit. The power input terminal is connected to the power output terminal through the voltage regulation sub-circuit, each of the linear constant current diodes is connected to the power output terminal, the linear constant current diode is used to connect a second number of UVC LEDs and keeps a working current of each UVC LED, and the voltage regulation sub-circuit is used for a constant output voltage.

A multi-channel constant current circuit and a lighting device are provided. The multi-channel constant current circuit is used to drive UVC LED to emit light, and includes a constant voltage circuit and a first number of linear constant current diodes. The constant voltage circuit includes a power input terminal, a power output terminal and a voltage regulation sub-circuit. The power input terminal is connected to the power output terminal through the voltage regulation sub-circuit, each of the linear constant current diodes is connected to the power output terminal, the linear constant current diode is used to connect a second number of UVC LEDs and keeps a working current of each UVC LED, and the voltage regulation sub-circuit is used for a constant output voltage.