An AC-DC power supply receives input AC power and outputs DC power. The converter includes a high power factor bridge rectifier, a barrier circuit with resistor(s) and capacitor(s), and a step-down switching DC-DC converter to step-down a first DC voltage to a second, lower, DC voltage for output. Additionally, fault-protection is provided by redundancy in diodes on diode legs of a bridge rectifier and capacitor(s) of a filter circuit thereof, and a fault-protection circuit to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

An AC-DC power supply receives input AC power and outputs DC power. The converter includes a high power factor bridge rectifier, a barrier circuit with resistor(s) and capacitor(s), and a step-down switching DC-DC converter to step-down a first DC voltage to a second, lower, DC voltage for output. Additionally, fault-protection is provided by redundancy in diodes on diode legs of a bridge rectifier and capacitor(s) of a filter circuit thereof, and a fault-protection circuit to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

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 dual-die device, a display device and a driving method thereof are provided. The dual-die device includes: a first light emitting die for emitting light containing short-wave blue light; a second light emitting die for emitting light from which short-wave blue light is filtered out; and a control circuit. The control circuit is connected to the first light emitting die and the second light emitting die, and configured to control the first light emitting die or the second light emitting die to be turned on.

A power system capable of preventing from mistakenly triggering an electric shock protection function of a lamp tube and the method thereof is provided. The power system includes a live wire input end, a neutral wire input end and a capacitive component. The live wire input end is connected to a first node; the first node is used to connect to the live wire terminal of the electric shock protection circuit of a first light-emitting module. The neutral wire input end is connected to a second node; the second node is used to connect to the neutral wire terminal of the electric shock protection circuit of the first light-emitting module. One end of the capacitive component is connected to the first node and the other end thereof is connected to the second node.

A leakage protection circuit and a dimming drive circuit are provided. A leakage detection circuit is configured to detect whether leakage occurs between two input terminals that receive an external signal. When leakage occurs, leakage protection measures are taken. A pulse generation circuit receives the sampling signal characterizing the voltage between the two input terminals to compare the sampling signal with two thresholds to control a detection path of the leakage detection circuit to be turned on or off according to a comparison result. The leakage detection path is enabled to be turned on twice by setting two pulse signals in a power frequency period, which can consider the leakage detection of the front-edge phase-cutting dimming and rear-edge phase-cutting dimming of the dimming drive circuit and has a wide range of applications.

A Light Emitting Diode, LED, based lighting device arranged for connection to an Alternating Current, AC, mains supply, comprising a zero-crossing detection module arranged for detecting a zero-crossing in an AC voltage supplied by said AC mains supply, a detection pulse module arranged for providing a detection pulse based on said detected zero-crossing, a human body detection module arranged for determining a current drawn from said AC mains supply during said provided detection pulse, and for determining presence of a human body based on said determined current, wherein said detection pulse module is arranged for providing said detection pulse during a rising, positive, edge of said AC voltage.

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.

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 small cell networking device mountable to a streetlight fixture includes circuitry for converting alternating current power into direct current (DC) power and providing a digitally stable ground for operation of the small cell device. The circuitry includes a transformer isolating a primary side from a secondary side of the circuitry. A switching 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, such as via an optical isolator. The controller directs the switching circuit based at least on the feedback and input from an auxiliary winding of the transformer.