The difference between linear power supply and switching power supply and design skills

The voltage feedback circuit of the linear power supply is in the working state, and the switching power supply refers to the switching state of the tube used for voltage adjustment to work in the saturation and cut-off areas. The output of this voltage amplifier is used as the input of the voltage regulating tube to control the adjustment tube to change the junction voltage with the change of the input, so as to adjust its output voltage, but the switching power supply changes the output voltage by changing the time of opening and closing the adjustment tube, that is, the duty cycle! From its main features:

The linear power supply technology is very mature, the production cost is low, the stability can be very high, the ripple is also very small, and there is no interference and noise of the switching power supply, but its volume is relatively large compared to the switching power supply, and the input voltage range is high; Switching power supplies, on the other hand, are the opposite.

The similarity between switching power supply and linear power supply can only be said to be power supply, and both can provide stable voltage according to certain specifications. The difference can be explained according to their working principle, the switching power supply is a power supply working in the switching state, and there is a negative feedback that can change the duty cycle of the power supply on and off according to the change of load, so as to achieve the purpose of voltage stabilization, so the voltage stabilization effect of the switching power supply is very good. The structure of the linear power supply is relatively simple, directly convert the power frequency alternating current into low voltage through the transformer and then connect a voltage regulator chip, the linear power supply has no negative feedback, so the voltage output can not be adjusted according to the load change.

Compared with the switching power supply, the linear power supply is only simple in structure, and there is no absolute advantage in the other, so the switching power supply is used in the basic market now that has some requirements for voltage regulation.

1. The linear power supply has low efficiency and large heat generation, but the ripple is small, which is more suitable for the processing of weak and small signal circuits.

2. The switching power supply has high efficiency and small heating, but the ripple is large, and the interference to weak and small signals is relatively large.

Linear power supplies are inefficient and are more suitable for weak and small signal circuits. The switching power supply has high efficiency and interference with weak and small signals. Big.

First of all,The main differences between switching power supplies and linear power supplies are the efficiency and the way the adjustment tube works.

According to the working state of the adjustment tube, we often divide the regulated power supply into two categories: linear regulated power supply and switching regulated power supply.

Linear regulated power supply is a kind of DC regulated power supply that was used earlier. The characteristics of linear regulated DC power supply are: the output voltage is lower than the input voltage; The response speed is fast, and the output ripple is small; Low noise generated by work; low efficiency (the LDO that is often seen now appears to solve the efficiency problem); High heat generation (especially high-power power supplies) indirectly adds thermal noise to the system.

Switching power supply is a kind of power supply that uses modern power electronics technology to control the time ratio of the adjustment tube to open and turn off, and maintains a stable output voltage. Its characteristics are: the output voltage can be higher than the input voltage, the noise generated by the operation is high, the efficiency is high, the volume is small, and the temperature rise is small.

Compared with switching power supplies and linear power supplies, the cost of both increases with the increase of output power, but the growth rate of both is different. The cost of a linear power supply is higher than that of a switching power supply at a certain output power point, which is called the cost reversal point. With the development and innovation of power electronics technology, the switching power supply technology is also constantly innovating, and this cost reversal point is increasingly moving to the low output power end, which provides a broad development space for the switching power supply.

Linear power supply. <>

Switching power supply (buck).

Hello: The difference between switching power supply and linear power supply is mainly from the principle. I'll give you this information on my computer.

Linear power supply mainly includes power frequency transformer, output rectifier filter, control circuit, and protection circuit.

The switching power supply mainly includes input grid filter, input rectifier filter, inverter, output rectifier filter, control circuit and protection circuit.

Linear power supply is the first alternating current through the transformer transformer, and then through the rectifier circuit rectification filter to obtain the unstable DC voltage, to achieve high-precision DC voltage, must be adjusted through voltage feedback output voltage, this power supply technology is very mature, can achieve a high degree of stability, ripple is also very small, and there is no interference and noise of switching power supply. However, its disadvantage is that it needs a large and bulky transformer, and the volume and weight of the required filter capacitor are also quite large, and the voltage feedback circuit is in a working state, and there is a certain voltage drop on the adjustment tube, and when the output is larger than the working current, the power consumption of the adjustment tube is too large, the conversion efficiency is low, and a large heat sink is installed. This power supply is not suitable for the needs of computers and other equipment, and will be gradually replaced by switching power supplies.

Hope it helps.

The same is the difference between the power supply, the linear and the switching balance power supply, do you know the smiling stool?

The adjustment tube of the linear power supply works in the amplified state, so the heat is large, the efficiency is low (about 35%), and it is necessary to add a large volume of heat sink, and it also needs a large volume of power frequency transformer, when you want to make multiple sets of voltage output, the transformer will be larger. The adjustment tube of the switching power supply works in the saturation and cut-off state, so the heat generation is small, the efficiency is high (more than 75%), and the large volume of the transformer is omitted. However, the DC output of the switching power supply will be superimposed on a large ripple (50mV at 5V output typical), which can be improved by connecting the voltage regulator diode at the output slag end.

Relatively speaking, the linear power supply does not have the above defects, and its ripple can be very small (less than 5mV).

The differences between switching power supply and linear power supply are as follows:

1. The loss of linear power supply is larger than that of switching power supply.

2. The efficiency of linear power supply is lower than that of switching power supply.

3. The external interference of linear power supply is smaller than that of switching power supply.

The working principle of switching power supply:

1. When the switch tube is on, the current flows out from the input power supply VIN to the switch tube SW.

2. to the output inductor LO, and finally to the output capacitor CO and load RL.

3. When the switch tube is cut-off, there is no current flowing out of the input power supply, and the load current is provided by the output inductor Lo and the output capacitor CO, due to the signal and answer energy storage effect of the inductor Lo, the current will flow through the freewheeling diode freewheeling D, as shown in the blue arrow direction of the figure below.

Features of Linear Power Supply:

1. The transistor has a cut-off area, an amplification area, and a saturation area, and when the transistor works in the amplification area, it can be found that it can be approximately regarded as a linear output by its output characteristics, so it can be used to build a linear power supply.

2. Another way: when an AC signal is input, we can first convert it into a DC signal through a rectifier bridge to filter the signal, and then stabilize the voltage of the voltage regulator tube, and finally the filter output can get the required voltage value.

3. The characteristics of linear power supply: the ripple is small, and the efficiency is generally not high. <>

Hello, dear. The senior will find out the following information for you, you can learn about it first: There is a clear difference between linear power supply and switching power supply. First, the linear power supply car can provide a constant DC output, while the switching power supply can provide an adjustable DC output.

Secondly, linear power supplies have lower efficiency, while switching power supplies have higher efficiency. In addition, the noise level of a linear power supply is higher than that of a switching power supply, whereas a switching power supply has a lower noise level than a linear power supply. In addition, linear power supplies are larger in size than switching power supplies, whereas switching power supplies are smaller in size than linear power supplies.

Finally, the cost of a linear power supply is higher than that of a switching power supply, while the cost of a switching power supply is lower than that of a linear power supply. In short, linear power supplies and switching power supplies have their own advantages and disadvantages, and the appropriate power supply mode should be selected according to different application scenarios. I hope mine can help you