The present disclosure generally relates to the field of fire alarms. The teachings thereof may be embodied in a strobe notification appliance having: a boost circuit connected to an input voltage; an energy storage circuit charged by the boost circuit; a drive circuit generating a drive current; an LED circuit with at least one LED element; a first sampling circuit collecting an overall voltage drop of all the LED elements; and a control circuit configured to adjust the drive circuit to supply a working current during an alarming stage and supply a detection current during a detection stage. The detection current is lower than the working current and thereby light energy produced by the LED elements during the detection stage is lower than alarming light energy produced during the alarming stage. During the detection stage, the control circuit determines whether the LED circuit works normally based on the collected overall voltage drop.

An auxiliary power system for powering an auxiliary circuit is connected to the same power source that powers the lighting element within a luminaire. The auxiliary power system may be connected to the output of the power source in series or in parallel with the lighting element. The power source may be an LED driver and the lighting element may include one or more LEDs or the power source may be an electronic ballast and the lighting element may be one or more fluorescent lamps.

A power supply, includes: a hot node coupled to a hot wire of an AC source, and a ground node coupled to an earth ground, where a neutral wire of the source is not present; a storage component, coupled to a return node and in series with a current limiter, where the current limiter enables the storage component to charge to a voltage while limiting leakage current to a prescribed value; a low voltage power supply including a buck-boost regulator, coupled to the storage component and to a return node that provides a reference voltage, where the low voltage power supply receives the voltage and generates an output voltage on an output node that is referenced to the reference voltage; and a wireless transceiver that employs the output voltage to transmit and receive messages from one or more corresponding wireless devices.

A power supply, includes: a hot node coupled to a hot wire of an AC source, and a ground node coupled to an earth ground, where a neutral wire of the source is not present; a storage component, coupled to a return node and in series with a current limiter, where the current limiter enables the storage component to charge to a voltage while limiting leakage current to a prescribed value; a low voltage power supply including a buck-boost regulator, coupled to the storage component and to a return node that provides a reference voltage, where the low voltage power supply receives the voltage and generates an output voltage on an output node that is referenced to the reference voltage; and a wireless transceiver that employs the output voltage to transmit and receive messages from one or more corresponding wireless devices.

Battery charge function may be in an LED driver which eliminates the duplication of line interface circuitry. A single line interface circuit provides the input power conversion for both the battery charge function and normal operation of the LED driver. During a loss of power, the LEDs may be controlled using power from the battery backup module.

A light-emitting diode (LED) lamp comprising a normally-operated portion and an emergency-operated portion is used to replace a luminaire operated only in a normal mode with alternate-current (AC) mains. The normally-operated portion comprises a second driving circuit whereas the emergency-operated portion comprises a rechargeable battery, a first driving circuit, a self-diagnostic circuit, and a control circuit. The LED lamp can auto-switch between the normal mode and an emergency mode according to availability of the AC mains and whether a rechargeable battery test is initiated. The control circuit is configured to produce a pulse train with a predetermined duty cycle to operate the first driving circuit while disabling the second driving circuit to eliminate operational ambiguity during the rechargeable battery test. The self-diagnostic circuit is configured to provide multiple sequences and to auto-evaluate battery performance by sending the pulse train to operate the first driving circuit according to the multiple sequences.

A light-emitting diode (LED) lamp comprising a normally-operated portion and an emergency-operated portion is used to replace a luminaire operated only in a normal mode with alternate-current (AC) mains. The normally-operated portion comprises a second driving circuit whereas the emergency-operated portion comprises a rechargeable battery, a first driving circuit, a self-diagnostic circuit, and a control circuit. The LED lamp can auto-switch between the normal mode and an emergency mode according to availability of the AC mains and whether a rechargeable battery test is initiated. The control circuit is configured to produce a pulse train with a predetermined duty cycle to operate the first driving circuit while disabling the second driving circuit to eliminate operational ambiguity during the rechargeable battery test. The self-diagnostic circuit is configured to provide multiple sequences and to auto-evaluate battery performance by sending the pulse train to operate the first driving circuit according to the multiple sequences.

A system for supplying a load comprising: an input inductor configured to receive an input voltage, a selection module connected to the inductor via a switching node, and a multi-level half-bridge stage comprising a plurality of half-bridge stages, each half-bridge stage comprising a pair of switches connected between a switching node; a power combining stage coupled to each half-bridge stage using parallel bus voltage lines output from the multi-level half-bridge stage, the power combining stage configured to output a voltage to the load; and a controller configured, based on the input voltage, to selectively control a half-bridge stage to operate in a half-bridge mode to provide a stepped-up voltage on a bus voltage line, wherein the controller is further configured to control the power combining stage to provide a voltage between the bus voltage lines and the sum of these voltages is higher than a peak of the input voltage.

A dimming module includes a triggering circuit, a control signal generating circuit, a voltage converting circuit, and a linear driving circuit. The triggering circuit is configured to control a trigger delay angle of an AC input voltage according to a dimming command, in order to output a first voltage signal correspondingly. The control signal generating circuit is configured to output a control voltage according to the first voltage signal. The voltage converting circuit is configured to output a DC operating voltage having an operating level according to the first voltage signal, and output the DC operating voltage to a lighting module, in which the lighting module includes a light-emitting diode. The linear driving circuit is configured to drive the lighting module according to the control voltage.

An apparatus to drive a multi-channel light emitting diode (LED) array includes switching transistors connected to LED strings of the multi-channel LED array, error amplifiers connected to the switching transistors, each of the error amplifiers being configured to control current flowing through the LED string to have a target magnitude, and overheating protection circuits connected to the switching transistors, each of the overheating protection circuits being configured to regulate current flowing through a respective switching transistor to have a magnitude less than or equal to the target magnitude.