Overheating protection of power adapter
No matter what electronic equipment, a long running time will increase the temperature, when the temperature is too high inevitably affect the function of the equipment, the power adapter is the same, when the temperature is too high, the internal function of the components will be affected, produce unstable factors.So in the ordinary power adapter has overheating protection.
The main heat sources of power adapters are schottky rectifier diodes, high frequency switching transformers, power MOS transistors and filter electrolytic capacitors.Power MOS transistors, high frequency transformers and rectifying schottky diodes have more prominent temperature rises.In order to prevent the power adapter from being damaged by overheating, the design of the power adapter requires not only the use of electronic components with good high temperature characteristics, but also reasonable design and advanced printed PCB board, radiator and high-frequency production process.Transformer, and take overheating protection measures, which is necessary to ensure safety conditions
Overheat protection types of power adapters can be classified into the following categories:
automatic reset, manual reset, non-regenerative, non-reset, and other types that provide equivalent overheat protection.
Overheat protection refers to starting the corresponding protection function when the temperature exceeds a certain threshold.Electrical equipment or machinery in operation due to energy conversion or friction generated heat, will lead to abnormal operation or failure.There are three ways of overheating protection, cutting off the operation of the equipment, reducing the operation performance of the equipment or improving the ventilation and heat dissipation conditions.Overheat protection prevents power supply from being a single entity, which is a concern.It might be hard to get away from the heat source.The most basic requirements of the placement is free from mechanical impact, easy to remove, polar protection function, cable, non-polar equipment connection terminal must have two cable overheating protection procedures, protection circuit disconnect, will not affect the normal operation of the network adapter, but can not cause fire or damage the electrical equipment.Under normal conditions, ac adapter circuit board space and cabinet space is relatively small, it has some problems and overheating protection.If overheat protection is difficult to assemble, use a temperature fuse or thermistor as thermal protection.Put it on the surface of the cooler, high frequency transformer or power MOS tube, the overheat protection switch will automatically turn off the power supply, when the temperature rises to a certain value, or force off the modulation pulse output to stop the high frequency oscillation.
In order to suppress the temperature rise of the power adapter, in addition to the power MOS tube with small leakage current and short storage time, the power MOS tube also needs to be equipped with a radiator fin.The stability of the power adapter will be greatly improved and the loss rate will be significantly reduced after installing the radiator fin on the MOS tube.The role of electronic switch overheat protection measures is to cut off the ac input line of the power adapter before the temperature of heat-prone components or power supply housing exceeds the specified limit, or force the modulation pulse output to stop high-frequency oscillation.