Introduction to Linear DC Regulated Power Supply
1) Transistor series DC stabilized power supply: The transistor series DC stabilized power supply works in a linear amplification state, so it has fast response, high voltage stability and load stability, small output ripple voltage, and low noise. In terms of circuit technology, its control circuit uses fewer components. There are no special requirements for the switching characteristics of the adjustment tube and the high-frequency performance of the filter, so the reliability is high.
A serious disadvantage of series regulated power supplies is their low efficiency. To improve efficiency, it is necessary to reduce the pressure drop on the regulating tube and reduce the loss on the regulating tube. Solution: ① PNP and NPN transistors are complementary: When the output power supply current of the series regulated power supply is large, the adjustment tube is usually connected to a Darlington combination tube with a common collector. Because when the electrical parameters of the transistors are the same and the current amplification factor is kept equal, the collector-emitter voltage drop of the complementary connected combined adjustment tube is reduced, so the efficiency of the power supply is improved; ② Bias method: general common collector combination The voltage drop between the tube collector and emitter depends to a certain extent on the bias current. The bias connection method can effectively improve the power supply efficiency when the output current is constant; ③ The switching regulator is used for pre-adjustment: When the input-output voltage difference is relatively large and the output current is also relatively large, a switching regulator is used Pre-regulation of series voltage regulators is also an effective way to improve power efficiency. Switch pre-regulation can also be set on the primary side of the power transformer.
2) Development of integrated linear voltage regulators: In the early market, there were many manufacturers of integrated voltage regulators with large output and wide applications. There are two main categories: semiconductor monolithic integrated voltage regulators and hybrid integrated voltage regulators. Their circuit forms, DC regulated power supply packages, voltage and current specifications are all diverse. Integrated voltage regulators can be divided into constant voltage, adjustable, tracking and floating. But no matter which form they are, they usually consist of a reference voltage source, a comparison amplifier, an adjustment component, a power transistor, and some form of current limiting circuit. Some integrated voltage regulators also have internal logic shutdown circuits and thermal cutoff circuits. Compared with voltage regulators composed of discrete components, the advantages of integrated voltage regulators are very obvious, including low cost, small size, ease of use, good performance, and high reliability.
3) Constant current source network voltage-stabilized power supply technology: The use of constant-current network voltage stabilization is a characteristic of current series voltage-stabilized power supplies. Using a constant current network can effectively improve the stability of the power supply. Constant current networks are commonly used in integrated voltage regulators. Series regulators composed of discrete components are also increasingly using constant current technology. Constant current can be achieved using components such as transistors, field effect transistors and constant current diodes. Constant current diodes are more convenient to use in series regulators with discrete components.
