A Design Of DC Stabilized Voltage Supply With Protection Circuit

Series feedback regulation stabilized voltage supply have some characters such as the output voltage range is unrestrained by components themselves and the performance index can be very high. So it widely used in large changes in load, high performance requirements of regulators. It also used where the output voltage adjustable. But it has something weakness such as the circuit is complicated, the bad over-load ability, especially instantaneous overload will lead to short circuit and damaged the component, so it must join components protection circuit. Aiming at the series power supply for the basic principle and introduced the protection circuit, and combined with 7805 three terminal voltage stabilizer circuit inside the deadline. This paper proposed a new type of stabilized voltage supply with cut-off type protection circuit.By functional division, this paper enlarged on every parts of the stabilized voltage supply. Input part adopts 220V ac input, 20V2A output transformer; Rectification and filtration part adopts a unidirectional bridge rectification circuit; Regulation part adopts series circuits with three NPN transistor which contain two low power and a high power; Sample part adopts two resistor and a potentiometer to output voltages mobilized in a small range; Reference voltage part adopts silicon zener diode; Comparison amplifier part adopts two transistor who has high voltage amplification factor as difference comparison amplifier; Auxiliary power supply part adopts double voltage rectification and voltage stabilizing diode as a output circuit; The protection part of stabilized voltage supply adopts a circuit with cut-off over current protection, when the protection tube start to work, the dynamic resistant is much bigger than the regulator tube, it's equal to cut-off. When the circuit put right, the protection tube stop working and the stabilized voltage supply back to work again. At last, the paper used PSpice part of OrCAD9.2 simulation software to simulate the whole circuit by Transient Analysis and DC Sweep Analysis.The results show that the stabilized voltage supply circuit can achieve the expected purpose. It has simple structure and high accuracy, and it's a more practical circuit with high practical value.