NTC thermistors in the field of switching power supply applications

Today Yufeite electronic to share with you about the application of NTC thermistor in the switching power supply:

      As a result of switching power supply has a high efficiency, energy transfer loss is small, the output is flexible and variable, occupying a small volume space and other general linear power supply are incomparable advantages and gained a wide range of applications. To date, large to large-scale electronic equipment power supply, small to household appliances, LED lights power supply almost without exception are used to switching power supply, it is the current unanimously recognised high-efficiency, low-power power supply. But low-power, high-efficiency conversion (AC-DC) is the cost of switching power supply in practical applications will also produce a lot of trouble, such as: EMC problems start-up inrush current problems, high-voltage high-current situation, with high value of the key components are prone to frequent damage, early failure of the phenomenon of the entire power supply system premature damage to appliances or equipment can not be used. This is the majority of line designers, especially power supply design engineers one of the more headaches.

 Figure 1 is one of the most basic switching power supply diagram, switching power supply is directly on the grid AC-220V (50Hz) AC power conversion process into a DC voltage we can 

directly use, very convenient and fast. The disadvantage is that under the fuse, will often open the B and C will fail for no reason, the transformer under the internal coil overheating, internal 

short-circuit and other phenomena occur, in addition to the components themselves can not be reliable. The occurrence of the above phenomena, most of the inrush current is too much, 

too big impact has a lot to do with. How can there be inrush current? Feng Gong from the time when the young have been trying to figure out. 

In practice have shown that, due to the existence of C1, any switching power supply, in the instant of power on will be the generation of inrush current, and the higher the load of the power

 supply, the higher the power, so the greater the inrush current. Practice has also proved: this surge current can be tens of times the normal operating current of the power supply to more 

than 100 times Oh, this is not alarmist Oh!

Even if it is a very short period of time, generally for the MS level, such a large current added to B1, C1 and T, a power on and off may not be damaged, a few times the power on and off 

does not seem to matter, but it is certain that every time you switch on and off, the relevant device is a damage. Years and years of switching machines, which is prone to problems. 

Engineers designed for this slow start, time-delay insurance and other means to avoid some failures, but can not be completely eliminated. Statistics show that: electrical equipment problems, 

more than 60% in the power system. Yu Gong is here to tell you, only 1 yuan cost, can be solved. Yu Gong, is an expert in the production and manufacture of NTC thermistors. Welcome to 

communicate with me!