Abstract: Provided are a constant-power pure sine wave output circuit, a device, and a power supply system. The circuit includes an AC-DC module, a charging module, a DC-DC boost module, a DC-AC output module, and an MCU module. The AC-DC module is electrically connected to the DC-DC boost module through the charging module, and the DC-DC boost module is electrically connected to the DC-AC output module. The MCU module is electrically connected to both the AC-DC module and the charging module. When there is a power outage, the first DC signal output by the AC-DC module will be lower than the preset DC threshold value, and the MCU module controls the charging module to transmit the second DC signal to the DC-DC boost module. Therefore, the circuit is capable of avoiding subsequent power outages, improving power supply stability, and meeting the requirements of applications with higher lighting demands.

Abstract: The application provides a downlight emergency power supply device, including an emergency power box having an accommodation cavity; a connection structure configured to fix a luminaire to the emergency power box, and comprising two clamping assemblies arranged oppositely, wherein the clamping assemblies are elastically connected to an outer side of the emergency power box; and a power supply assembly, fixed in the accommodation cavity, and configured to supply power to the luminaire; wherein the two clamping assemblies clamp and fix the luminaire in an inward or outward rebound state. By setting two clamping assemblies to clamp and fix the luminaire on the emergency power supply, it is simpler and less time-consuming to assemble than the screw mounting method used in the related art, without the need for manual screwing. Besides, the two clamping assemblies of the connection structure can be automatically clamped, achieving semi-automatic assembly, which is convenient and efficient.