What is the difference between a linear regulated power supply and a switching power supply
The linear regulated power supply changes and controls its output voltage and current by changing the conduction degree of the transistor. In the linear regulated power supply, the transistor is equivalent to a variable resistor, which is connected in series in the power supply circuit. Since the varistor flows the same current as the load, it dissipates a lot of energy and heats up, resulting in low voltage conversion efficiency. A common characteristic of linear regulated power supplies is that its power device adjustment tube works in the linear region, and the output is stabilized by adjusting the voltage drop between the tube electrodes. Due to the large static loss of the adjustment tube, it is necessary to install a large radiator to dissipate heat. Since the transformer of the linear power supply works at the power frequency (50Hz), the quality is relatively large.
Linear regulated power supplies are often used in low-voltage applications, such as LDOs that need to meet a certain voltage difference. The output voltage adjustment rate and ripple are relatively good, the efficiency is relatively low, the peripheral components required are relatively small, and the cost is low. The circuit is relatively simple.
The advantages of linear regulated power supply are high stability, small ripple, high reliability, and it is easy to make a multi-channel output continuously adjustable power supply. The disadvantage is that it is bulky, cumbersome, and relatively inefficient. There are many kinds of this kind of regulated power supply, which can be divided into regulated power supply, regulated current power supply and regulated voltage and current (bistable) power supply integrating regulated voltage and regulated current from the output properties. From the point of view of output value, it can be divided into fixed output power supply, band switch adjustment type and potentiometer continuously adjustable type. From the output indication, it can be divided into pointer indication type and digital display type.
The switching power supply is suitable for the full voltage range, does not require a voltage drop, and can use different circuit topologies to achieve different output requirements. The adjustment rate and output ripple are not as good as the linear power supply, and the efficiency is high. Many peripheral components are required and the cost is high. The circuit is relatively complex. The circuit types of switching DC power supply mainly include single-ended flyback, single-ended forward, half-bridge, push-pull and full-bridge. The fundamental difference between it and the linear regulated power supply is that the transformer in the circuit does not work at the power frequency but works at tens of kilohertz to several megahertz. The power tube does not work in the linear region, but in the saturation and cut-off region, that is, it works in the switching state; the switching DC power supply is named after this.
