A more thorough explanation of the linear controlled power supply's operating concept
We frequently categorize regulated power supplies into two groups based on the functioning condition of the regulating tube: switching regulated power supplies and linear regulated power supplies. There is also a tiny Zener tube-powered power supply.
The DC regulated power supply in which the regulator tube operates in a linear condition is referred to as the linear regulated power supply here. In order to understand how the adjustment tube operates in a linear condition, consider the following: RW is continuously variable, or linear (see the analysis below). In the switching power supply, it is different. The switching tube operates in two states: on and off: on, the resistance is extremely tiny; off, the resistance is very small big. In the switching power supply, we typically refer to the adjusting tube as a switching tube. Of course, a tube operating in an on-off state is not doing so in a linear manner.
An older style of DC regulated power supply is the linear regulated power supply. The LDO that is frequently seen now appears to solve the efficiency problem. However, the linear regulated DC power supply has the following characteristics: the output voltage is lower than the input voltage; the response speed is quick; the output ripple is small; the noise generated by the work is low; the efficiency is low; and large heat generation (especially with high-power power supplies), which indirectly increases thermal noise to the system.
Working principle: The following illustration will show how a linear controlled power source regulates voltage.
Uo=UiRL/(RW+RL), hence the output voltage can be altered by varying the size of RW. Please notice that in this formula, if we only consider the variable resistor RW's value change, the output of Uo is not linear; however, if we consider both RW and RL, the output of Uo is linear. Also take note of the fact that our figure shows the lead-out of RW to the right rather than the left. The image on the right only depicts the notions of "sampling" and "feedback," even if there is no difference from the formula; the majority of genuine power supply operate in the manner of sampling and feedback. The feedforward approach is only occasionally used below, or it is only used as an auxiliary method.
Let's move on: If we replace the variable resistor in the diagram with a triode or field effect transistor, and regulate the resistance of this "varistor" by sensing the output voltage, so that the output voltage is constant, we can Voltage stabilization succeeds in its goal. This triode or field effect tube is referred to as an adjustment tube since it is used to modify the voltage output.
Since the regulator tube is connected in series between the power supply and the load, it is called a series regulated power supply. Correspondingly, there is also a shunt-type regulated power supply, which is to adjust the output voltage by connecting a regulator tube in parallel with the load. The typical reference voltage regulator TL431 is a shunt-type voltage regulator. The so-called parallel connection means that like the voltage regulator tube in Figure 2, the "stability" of the emitter voltage of the attenuating amplifier tube is ensured by shunting. Maybe this figure does not let you see that it is "parallel connection", but On closer inspection, it is indeed so. However, everyone should pay attention here: the voltage regulator tube here works in its nonlinear region, so if you think it is a power supply, it is also a nonlinear power supply. In order to make it easier for everyone to understand, let's look back at a reasonably suitable picture until we can understand it concisely.
Since the adjusting tube is equivalent to a resistor, it will generate heat when the current flows through the resistor, so the adjusting tube working in a linear state will generally generate a lot of heat, resulting in low efficiency. This is one of the most important disadvantages of linear regulated power supplies. For a more detailed understanding of linear regulated power supplies, please refer to textbooks on analog electronic circuits. Here we mainly help you clarify these concepts and the relationship between them.
