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The switching power supply is an input AC voltage (AC) that is rectified and filtered to obtain a high-voltage DC voltage (DC=1.4AC). This voltage is connected to the switching element and used as a switch in a high-frequency state of 20KHZ~100KHZ. At this time, the DC high voltage will be cut into a high-frequency square wave signal. This square wave signal passes through the power NTC thermistor, and the preset voltage value can be obtained on the secondary side, and then can be obtained through rectification and filtering. required DC output voltage.

After the NTC thermistor completes the function of suppressing the surge current, due to the continuous action of the current passing through it, the resistance value of the power NTC thermistor will drop to a very small level. The power it consumes is negligible and will not affect normal operation. Therefore, using a power NIC thermistor in the power circuit to suppress the surge during startup is the simplest and most effective measure to protect electronic equipment from damage.

The thermistor used in the switching power supply requires a large ratio of cold resistance to thermal resistance and a fast response speed. The 0.7D20 thermistor used by Nanjing Shiheng Electronics in the switching power supply has a resistance value of 0.7 at 25°C and zero power. Ω, the body size is about 20MM, and the maximum steady-state current is 10A. Connecting one or more this thermistor in series in the power circuit can meet the needs of various use conditions of the switching power supply. If five of this product are connected in series, the cold-state resistance reaches 3.5Ω, and the maximum steady-state current still reaches 10A. The effect of suppressing surge resistance has been greatly improved. The 0.7D20 thermistor has passed a series of rigorous tests. As shown below:

With its unique process methods and leading technology, Nanjing Shiheng Electronics produces NTC thermistor products with outstanding advantages such as high precision, high reliability, and high stability. It is at the leading level in the industry. The power type NTC thermistor it produces suppresses It has strong surge current capability. The maximum capacitance in the internal control standard is two levels higher than the standard value. Especially the B value is large, the residual resistance is small, the same electrical performance is smaller, the power consumption is lower, and the main power type The product series has passed UL, TUV, and CQC safety certifications. The power thermistors produced by Shiheng Electronics have excellent performance and are favored and praised by switching power supply users!