The transformerless non-isolated socket switch is the s […]
The transformerless non-isolated socket switch is the simplest circuit structure in the socket switch. Part of the input and output of this type of power supply is common, and the input and output cannot be isolated. Its application range is limited, but because there is no transformer, the working principle of this kind of socket power supply is easy to understand, and there is no fault caused by transformer leakage. The buck socket switch (ie, buck switching regulator) is one of the non-isolated switching power supplies. The so-called buck type means that the output voltage is always lower than the input voltage regardless of whether the input voltage is positive or negative. Therefore, the step-down type socket switch is more suitable for applications where a small high-efficiency outlet switching power supply is required.
Below is an example of a buck switching regulator.
The main technical indicators are as follows.
(1) Input voltage: 20-70V DC.
(2) Output voltage: 0-25V DC.
(3) Output maximum current: 10A.
(4) Conversion efficiency: greater than 70%.
(5) Output ripple: less than 20mv.
It is mainly composed of a main circuit, a control and drive circuit, and a protection circuit. The main circuit is mainly composed of power field effect transistor VT1, power diode VD5 filter inductor L1 and filter capacitor C10; control and drive circuit is composed of UC3845 current control type chip and pulse transformer T1 and other peripheral circuits produced by ON Semiconductor; protection circuit It mainly includes a buffer network composed of R1, C2, and VD1, a current protection circuit composed of a current transformer T2, a diode VD2, and the like.
