A LED driving circuit based on a T-shaped lamp tube including: an input rectifying circuit, a Buck circuit, an IC power supply circuit, a PWM control integrated circuit, a compatible electronic ballast circuit, and an output rectifying and filtering circuit. The present application can realize the compatibility of single-ended input of AC mains, double-ended input of AC mains and double-ended input of an electronic ballast, and is simple in circuit, small in size, high in efficiency and stable in performance.

A light source device according to an embodiment includes: a first resistor (101) that is connected to a given potential; a light emitting element (12) that is connected in series to the first resistor; a second resistor (102) that is connected to the given potential; and a first current source (104) that is connected in series to the second resistor and that is configured to supply a freely-selected current within a given range are included. A first voltage is taken out from a first connection part where the first resistor and the light emitting element are connected to each other and a second voltage is taken out from a second connection part where the second resistor and the first current source are connected to each other.

A LED driving circuit based on a T-shaped lamp tube including: an input rectifying circuit, a Buck circuit, an IC power supply circuit, a PWM control integrated circuit, a compatible electronic ballast circuit, and an output rectifying and filtering circuit. The present application can realize the compatibility of single-ended input of AC mains, double-ended input of AC mains and double-ended input of an electronic ballast, and is simple in circuit, small in size, high in efficiency and stable in performance.

The present application discloses an illuminating device and a method for driving the illuminating device. The illuminating device comprises: an LED illuminating module; a mains supply operation module, comprising an LED driving unit; and a ballast operation module, comprising a simulation filament unit, a first detection unit, a second detection unit, a switch unit, a first start unit and a second start unit; wherein when the illuminating device is in a mains supply operation mode, the LED driving unit is used for driving the LED illuminating module; when the illuminating device is in a magnetic ballast operation mode, the first detection unit detects a voltage signal or frequency signal of the simulation filament unit and outputs a first detection signal, and after receiving the first detection signal, the first start unit enables the switch unit to be in a conducting state and drives the LED illuminating module; and when the illuminating device is in an electronic ballast operation mode, the second detection unit detects a voltage signal or frequency signal across both ends of the illuminating device and outputs a second detection signal, and after receiving the second detection signal, the second start unit enables the switch unit to be in a conducting state and drives the LED illuminating module.

An apparatus attachable to a luminaire includes circuitry for converting alternating current power into direct current (DC) power and providing a digitally stable ground for operation of a processor-based device. The circuitry includes a transformer isolating a primary side from a secondary side of the circuitry. A switching controller (e.g., a pulse width modulation controller) on the primary side directs a switching circuit to selectively permit current flow through a primary side of the transformer to a first ground node. A secondary winding of the transformer sources a rectified DC output relative to a second ground node that is isolated from the first ground node. In some cases, compensation on the secondary winding side provides isolated feedback to the controller, such as via an optical isolator. The controller directs the switching circuit based at least partially on the feedback and input from an auxiliary winding of the transformer.

A circuit is provided for converting alternating current power into direct current (DC) power and providing a digitally stable ground for operation of a processor-based device. Embodiments of the circuit include a transformer isolating (e.g., via galvanic isolation) a primary side from a secondary side of the circuit. A controller (e.g., a pulse width modulation (PWM) controller) on the primary side directs a switching circuit to selectively permit current flow through a primary side of the transformer to a first ground node on the primary side. A secondary winding of the transformer sources a rectified DC output relative to a second ground node that is isolated from the first ground node. In some cases, compensation on the secondary winding side provides isolated feedback to the controller via an optical isolator or some other circuit. The controller directs the switching circuit based at least in part on the error correction feedback and input from an auxiliary winding of the transformer.

A circuit is provided for converting alternating current power into direct current (DC) power and providing a digitally stable ground for operation of a processor-based device. Embodiments of the circuit include a transformer isolating (e.g., via galvanic isolation) a primary side from a secondary side of the circuit. A controller (e.g., a pulse width modulation (PWM) controller) on the primary side directs a switching circuit to selectively permit current flow through a primary side of the transformer to a first ground node on the primary side. A secondary winding of the transformer sources a rectified DC output relative to a second ground node that is isolated from the first ground node. In some cases, compensation on the secondary winding side provides isolated feedback to the controller via an optical isolator or some other circuit. The controller directs the switching circuit based at least in part on the error correction feedback and input from an auxiliary winding of the transformer.

Systems and methods are disclosed herein for monitoring light emissions in electronic devices. The disclosed techniques herein provide for determining a display duration of display devices for a user. Light emission profiles for each of the display devices are determined. A cumulative emissions exposure is determined that is based on the light emission profiles for the display devices and the display duration of the display devices for the user. A determination is made whether the cumulative emissions exposure exceeds a light emission exposure limit set for the user. In a positive determination, an instruction is transmitted to the display devices for execution of a remedial action based on predefined rules.

A tubular solid state lighting device has a pin safety circuit electrically connected to connection pins of the one end. The pin safety circuit comprises two protection components, of different types. In one set of examples, there is an electrically controlled isolation switch and an electronic switch which functions as a high voltage isolation barrier. The switch provides full galvanic contact separation, whereas the isolation barrier provides current protection if the isolation switch is not functional. In another set of examples, there is a mechanically controlled isolation switch and an electrical or electronic isolation barrier. This provides two levels of protection, but requiring only a single manual operation by the installer of the lighting device. It avoids end-of-life protection circuitry being triggered during the installation of the lighting device.

A tubular LED lamp designed for connection to a high frequency ballast. An electrically conductive screen is provided with an electrical connection between an internal node, such as an internal LED ground, and the screen. This provides a low impedance path5 for leakage currents which bypasses the LED string and thus prevents glow.