Switching power supply technology: Analysis of the internal structure of PC power supply

We need to see what the power supply is made of. The best way is to open the outer casing of the power supply and take a look at its internal structure.

The second method is to package four diodes together. The latter method is called a full bridge. The minimum withstand voltage and maximum current that a full bridge and a diode can withstand are limited: the withstand voltage should not be less than 700V, and the maximum current should not be greater than 1A.

4. Switching transistor

The switching transistor is the central hub of the switching power supply. It is mainly responsible for sending DC power to the switching transformer. Its withstand voltage cannot be less than 800V, and the output current is usually not less than 5A. The switching transistor is a component that is easily damaged, and it is the core of the switching power supply. Therefore, the quality of the switching transistor is closely related to the quality of the power supply.

5. Switching transformer

In the power supply, the metal wire package between the two heat sinks is the switching transformer we see. Its main function is to convert high voltage to low voltage. According to the principle of electromagnetism, its conversion ratio is mainly determined by the number of turns of the coil. A larger switching transformer can transfer more energy, so it is the first choice for high-quality power supplies. Those inferior power supplies are just small switching transformers to get the job done.

6. Control/protection circuit

The control/protection circuit controls every action of the power supply and is the brain of the power supply. It is responsible for starting the power supply and monitoring and adjusting the voltage. At the same time, it automatically protects against short circuit, open circuit, overvoltage, overcurrent, undervoltage, undercurrent, etc. Inferior products often simplify the control circuit or even do not have a protection circuit. All of this brings many hidden dangers to the use of computers.

7. Power supply fan

The power supply fan is an important part of the power supply, which is responsible for extracting the hot air from the power supply. When you open the power supply, you can see two large heat sinks. The performance and limit parameters of the high-power tubes on the heat sinks directly affect the safe power carrying capacity and product cost of the power supply. The size of the power margin is closely related to the specific power tube model. Whether a power supply is genuine or not can be seen at a glance by opening the iron box. The 220V AC input socket of the high-end power supply uses an integrated socket with a filter. Although this will increase the cost by nearly 20 yuan, it is good for purifying the power supply and absorbing surge current.

8. Others:

In addition, the two sockets at the back of the power supply are used to connect to the external power supply and provide a socket for the monitor. Generally, the male socket is the power socket. There is a voltage setting switch between the two sockets to switch between 110V and 220V. The 220V voltage standard is widely used in China. If it is set to 110V by mistake, it will cause damage to the power supply.

Many ATX power supplies have eliminated the monitor socket and installed a power switch in its place. This is a real physical power cut-off switch, which is fundamentally different from the POWER button on the front of the ATX case. It also reduces the power that the power supply provides to the monitor, thereby extending the life of the power supply and the life of the monitor.

ATX power supplies provide multiple sets of plugs, mainly 20-pin motherboard plug, 4-pin drive plug and 4-pin small drive special plug. There is only one 20-pin motherboard plug and it is directional, which can effectively prevent mis-insertion. The plug also has a fixing device that can hook the socket on the motherboard to prevent the connector from loosening and causing the motherboard to suddenly lose power when it is working.

The four-core drive power plug is the most widely used. All CD-ROMs, DVD-DOMs, CD-RWs, hard disks and even some fans need it. The four-core plug provides two sets of voltages, +12V and +5V. Generally, the yellow wire represents the +12V power supply, the red wire represents the +5V power supply, and the black wire represents the 0V ground wire. This four-core plug power supply provides the largest number of power supplies. If the user still does not have enough, a one-to-two adapter cable can be used. The principle of the four-core small drive special plug is the same as that of the ordinary four-core plug, but the interface form is different. It is specially designed for traditional small drive power supply.

There are many version structures of ATX power supply, including ATX 1.0, ATX 1.1, ATX2.01, ATX2.02, etc. Currently, ATX2.01 is the main one. For high-end chassis or high-end power supplies purchased separately, there are ATX2.02 version products.