Contact Us

ADD:5th Floor ,22nd Building,3rd Industrial Fenghuang Xingwei Village,Fuyong Town,Bao'an District,Shenzhen China.
Site:Home > Technical Article > Text

 Technical Article

Power Adapter Overheat Protection Circuit

Heat resistance and fire performance of the power adapter is not only directly related to the reliability and service life of the power adapter, but also directly related to the degree of the risk of fire, related to the safety of the lives and property of the user.
Power adapter main heat source Schottky rectifier diodes, high-frequency switching transformers, power MOS filtering electrolytic capacitors, power MOS high-frequency transformer and rectifier Schottky diode temperature rise is more prominent. Power adapter damage due to overheating, not only requires the use of high-temperature characteristics of a good electronic components in the design of the switching power supply adapter, also asked the printed PCB board, the heat sink, high-frequency transformer design is reasonable, advanced production technology, and the need to take in order to prevent overheating protection measures, which are designed to guarantee the security must have the condition.
In addition to the selection of leakage current, short storage time power MOS in order to suppress the temperature rise of the power adapter, you need to give the power MOS installation of the heat sink. Proved MOS tube to install the heat sink, the stability of the power adapter will greatly improve the loss rate was significantly lower. The role of the electronic switch overheat protection measures is easy to heat in the power adapter components or power supply enclosure temperature exceeds the set limit before you disconnect the AC adapter AC input line, or forced to shut down the modulation pulse output, stop the high-frequency oscillation.
Power adapter overheating protection can be divided into the following categories: automatic reset, manual reset type, can not be updated, reset and various other types of protection equivalent to overheat.
The overheating protection switching power supply constitutes a whole, need to pay attention to the placement accept the distance from the heat source, can be replaced Difficult. Placed the most basic requirement is not subject to mechanical impact, easy removal; protection function and polarity, cord-connected, plug without polarity equipment should have two leads overheat protection control; protection circuit is disconnected, does not affect the normal operation of the power adapter, but can not cause a fire or damage to the electrical equipment. The usually power adapter circuit board area and the plastic housing space are relatively small, has some difficulties with overheating protection. If the overheating protection is difficult to assemble into, temperature fuse or thermistor can be used as a thermal protector. Paste it on the the heatsink surface of the high-frequency transformer or power MOS, overheating protection switch will automatically cut off the power when the temperature rises to a certain value, or forced to shut down modulation pulse output stop the high-frequency oscillation.
If the power adapter with a control driver IC with overheating protection function, then do not need to add any external components or only need to add very few external components, can play overheat protection. Because the power adapter control driver IC has a built-PN junction temperature sensor containing thermal shutdown circuit. PN junction temperature sensor does not have a built-driven IC, connected to a temperature sensor element in its external. The driver IC thermal shutdown circuit, overheat protection becomes very simple, and integrated circuit itself, the price is also very low, the cost performance is very high.


Next:The Filter in The Power Adapter Circuit  Prev:The Difference between Power Adapter and Charger

© 2013 Shenzhen Jihongda Power Co.,Ltd All Rights Reserved USB Charger-Switch Mode Power Supply-Power Adapter