Second, the originator of PC power supply-AT power supply specification

AT power supply is a veteran of PC power supply, and its power is generally 150W~250W ~ 250W. * * It has four outputs (5V, 12V) and provides a P.G (good power supply) signal to the motherboard. The output line is two 6-core plugs and several 4-core plugs, and the two 6-core sockets supply power to the motherboard. AT power supply is turned off by cutting off, that is, "hard shutdown".

Before ATX power supply appeared, computers from 286 to 586 were mainly AT power supply. AT present, AT power supply has withdrawn from the market, even in the old computer market, it is difficult to see it.

Third, the evolution of AT power supply specification-ATX power supply specification

ATX specificATion is a new main board structure standard formulated by Intel in 1995, which is the abbreviation of English (AT Extend) and can be translated into at extended standard. ATX power supply is designed according to this specification. Compared with AT power supply, the overall scale of ATX power supply has not changed much. The most significant difference between ATX power supply and AT power supply is that the former cancels the traditional mains switch and relies on the combination of +5Sb and PS-ON control signals to realize the on-off of the power supply. ATX power supply has six outputs, namely +5V, -5V,+12V,-12V, +3.3V and +5Sb.

+5Sb is the power supply of the host system in the standby state of ATX, and it is also the working power supply of the automatic management and remote wake-up communication related circuits. In standby and controlled start-up, its output voltage is 5V high level, and it is led out from pin 9 of ATX plug with purple wire. PS-ON is the control signal of host power supply or network computer remote wake-up power supply. Different types of ATX switching power supplies have different standby voltages of 3V, 3.6V and 4.6V. ..

The main feature of ATX power supply is that it does not use the traditional mains switch to control whether the power supply works or not, but uses the combination of "+++5VSB and PS-ON" to switch the power supply. As long as the signal level of "PS-ON" is controlled, the power supply can be turned on and off. S-ON control circuit in power supply is controlled by PS-on signal. When "PS-on" is less than 1V, the power supply is turned on; when it is greater than 4.5V, the power supply is turned off.

The trigger button switch (non-locking switch) on the surface of the main chassis controls the output state of the "power monitoring component" of the motherboard, and it can also control the output of the "power monitoring component" through programs: for example, under the WIN XP platform, the ATX power supply will be automatically turned off by issuing a shutdown command to make "PS-On" become +5V .. When power is cut off, the output signal of PW-OK disappears several hundred milliseconds earlier than the output voltage of the ATX switching power supply+5V.

AT present, the ATX power supply on the market, whether brand power supply or miscellaneous power supply, is generally developed on the basis of AT power supply by making appropriate changes in circuit principle. Therefore, the ATX power supply we bought is basically similar in circuit principle. Since this publication, the specification of ATX power supply has gone through the stages of ATX 1.0, ATX 1, ATX 2.0, ATX 2.0 1, ATX 2.02, ATX 2.03 and ATX 12V. At present, most power supplies on the market follow ATX 2.03 or later.

Differences between 1, ATX 1. 1 and ATX2.0 standards.

The air path inside the ATX power supply is adjusted, and the fan that used to supply air to the inside of the chassis is changed to exhaust air to the outside of the chassis. PS_ON#, PWR_OK signal and +5Sb power supply specification are supplemented, and the terminal voltage variation range of +3.3VDC and soft power supply control signal are redefined. Add optional fan auxiliary power supply, fan monitoring, IEEE 1394 voltage and 3.3V remote control voltage. The definition of internal wiring color of power supply is supplemented.

2. Differences between 2.ATX2.00 and ATX 2.0 1

The definition of I/O interface between chassis and motherboard is modified and supplemented. The output current of +5Sb is increased from 10mA to 720mA, which improves the ability of the motherboard to wake up devices and improves compatibility.

3. The difference between ATX2.01and ATX 2.02 standard.

A new auxiliary power connector (6-core connector, similar to the connector used on AT motherboard) has been added for power supplies above 250-300 W. ..

The contents of the technical white paper are modified and supplemented, and the relationship between PS_ON, PWR_OK and related voltages when the power supply is started is explained, and the power supply definition of IEEE 1394R channel is defined. According to Intel's ATX Voltage Source Design Manual (version 0.9), two errors in the original technical white paper were corrected, and the voltage fluctuation range of the original -5VDC and-12VDC was changed from the original 5% to 10%.

4. The difference between 4.ATX2.02 and ATX2.03 standards.

Among them, ATX 2.03 standard adopts +5V and +3.3V voltages, which directly provide the required voltages for high-power processors and graphics cards. Single-channel+12V output is mainly used in hard disk and CD-ROM devices, because the power consumption of processor and graphics card was relatively low at that time, so all components were safe. But the launch of P4 processor changed all this. Because of the high power consumption of +5V voltage, it can not provide enough current when using products conforming to ATX 2.03 specification. Based on this, Intel revised the ATX standard and introduced the ATX 12V 1.0 specification.

5.ATX 12V standard

The main difference between ATX 2.03 and ATX 2.03 is that the power supply voltage of CPU is+12V instead of the previous +5V voltage. In this way, the output voltage of+12V is strengthened, and the load is much higher than +5V, which solves the problem of high power consumption of P4 processor. The most obvious change is that an independent 4Pin power interface is added to the CPU for the first time, and the P4 processor is powered by the output voltage of+12V. In addition, the ATX 12V 1.0 specification also makes corresponding provisions on surge current peak value, filter capacitor capacity and protection circuit. , to ensure the stability of power supply.

However, with the appearance of Prescott CPU, the system requires higher output current of 12V, and the carrying capacity of wires is limited, which requires higher output current of CPU of+12V. So the power supply is also from ATX 12V 1.0, ATX1.1,ATX 12V 1.2, ATX1. ..

ATX 12V 1.3 version

ATX 12V 1.3 mainly enhances the power supply of 12V, and at the same time increases the power interface to SATA hard disk, which improves the conversion efficiency of power supply. The single-channel output of+12V can be completely higher with the current power supply technology, but it will lead to greater safety hazard and line loss of its output line. Therefore, Intel specifically limits the single-channel output of+12V to be no more than 240VA. In addition, ATX 12V 1.3 also cancelled the supply of -5V voltage.

Originally, the voltage of -5V was used for ISA slot, but with the elimination of ISA slot, the voltage of -5V was no longer used, so the power supply of -5V was officially cancelled in ATX 12V specification, so some newer power supplies did not output this voltage at all. At the same time, in the specification of ATX 12V 1.3, the power efficiency of full load is improved from 68% to 70%. However, with the appearance of PCI-E devices, the power consumption of the system is rising again, and the demand for+12 VDC continues to increase.

Although the single channel output of ATX 12V 1.3 can be completely higher, it will lead to greater safety hazard and line loss of its output line. Therefore, Intel specifically limited the single-channel output of+12V to no more than 240VA. Without changing the output specification of ATX power supply, the traditional ATX 12V 1.3 power supply can no longer meet all hardware requirements by changing its internal design, so a higher specification ATX 12V 2.0 came into being.

ATX 12V 2.0 version

Compared with ATX 12V 1.3, the most obvious improvement of ATX 12V 2.0 is that+12V adds one output, that is, it adopts two outputs, one of which is+12V (called+12v).

If the output of a computer's switching power supply ++ 12VDC is 22A, it is not allowed for safety. The FCC (Federal Communications Commission of the United States) has made very clear regulations in this regard, and any DC voltage output of computer power supply is not allowed to exceed 240 VA. For example, if the output voltage of a certain path is 40V, the current of the path is at most 240VA divided by 40V and equal to 6A before the current reaches 6A.

Intel's expected output requirement for ++ 12VDC is 22A, which has exceeded the FCC's requirement for safety and reached+12V× 22A = 264VA, far exceeding the requirement of 240VA. This is not allowed in terms of security. Under this technical background, Intel divides the ++ 12VDC of ATX 12V2.0 into+12V 1DC and++12vdc.

+12V 1DC supplies power to the motherboard and PCI-E graphics card through the main power interface (12×2) to meet the memory requirements of PCI Express X 16 and DDR2; And ++ 12V2DC supplies power to Prescott CPU through (2×2) interface.

This design can scientifically solve the safety problem of 240VA. In fact, the wiring of+12V 1DC and ++ 12V2DC on the motherboard is completely separated. The specification of ATX 12V2.0 has some not obvious changes, such as the output load can meet the requirements of the latest hardware, and a second+12V connector is added to the processor, so that the remaining 12V power supply will not be unstable due to the sudden loading of the processor. Because of the dual-channel 12V output, the main power interface is changed from 20Pin to 24Pin output.

Although many manufacturers have provided the old version of the 24pin motherboard adapter to replace the developed ATX 12V 2.0 power supply, although there is no major problem in use, it is only a temporary replacement and cannot completely replace the genuine ATX 12V2.0 power supply, because this has the following shortcomings: First, it cannot improve the phenomenon of insufficient+12V2. It can't meet the strong demand of the new system for the increase of +65433, especially the low wattage power supply specification of the old version before ATX12V1.3, and+12V is seriously insufficient. Adding a 24pin motherboard adapter to the old version of the power supply is just a trick of deceiving yourself. The second problem is the pressure drop caused by the adapter. Because the output demand of+12V is large, if the connecting wire is not well designed, it will form a serious voltage drop problem and affect the power supply quality.

20 stitches on the left and 24 stitches on the right.

The left side has 20 turns and 24 stitches, and the right side can be disassembled with 24 stitches.

Although some different connectors have been added, using jumper or special 20-or 24-pin ATX connectors can still be compatible with the old specifications. It is important that when your old power supply is damaged, you can safely replace it with 2.0 1 power supply to ensure normal use. In terms of output interface, another new change of ATX 12V 2.0 is the power connector of SATA hard disk drive, which was originally included in ATX 1.3 standard, but it is no longer needed, which means that the era of adapter conversion is over, and they have verified most applications, especially on major hard disks. After all, the ATX standard does not limit how many connectors need to be installed.

In addition, the Intel ATX 12V2.0 version also has an important improvement, that is, the conversion efficiency has been improved. Because some electric energy is converted into heat and lost during the operation of the power supply, the power supply must minimize the heat loss. Conversion efficiency is the percentage of output power divided by input power. Under full load, the minimum conversion efficiency of 1.3 power supply is required to be 68%. Version 2.0 improves the recommended conversion efficiency to 80%. Although both power factor and conversion efficiency refer to the utilization rate of power supply, they are quite different.

Simply put, the loss caused by power factor is the burden of power department, while the loss of conversion efficiency is the burden of users themselves. Power factor, EMI circuit, etc. It is the protection of the national grid. That is to say, the efficiency of power conversion is not 100%, but part of it is converted into heat. For example, the power efficiency of the V 1.3 version is only 68%, which means that 32% of electric energy is converted into heat energy. In order to prevent the accumulation of heat from affecting the normal operation of the computer, we have to dissipate the heat, which is why we installed the fan.

ATX 12V2.0 standard can reach 70% under peak load and general load, and 60% under low load. The suggested efficiency values can reach 75%, 80% and 68% respectively under peak load, normal load and low load (the so-called normal load refers to half of the full load output value, and the low load is 20% of the full load output value). However, if you underestimate the power consumption converted into heat energy, for the 400W power module, you will waste a lot of electricity instead of contributing to the computer. If you use a less efficient power supply, it is actually very common. You should be able to see the painful price from your electricity bill. You only need to simply use a good power supply, and you may spend a little more money at first, but it will definitely contribute a lot to the money saved in the future, especially if you need to keep your computer on all day.

According to the development of its own system platform, Intel recommended four power specifications in ATX1V2.0, namely ATX1V2.0 version 250W, ATX1V2.0 version 400W, ATX1V2.0 version 350W and ATX/KLOC-0. It is worth noting that not all motherboards support ATX 12V2.0 power supply-this power supply must match motherboards conforming to ATX 12V 2.0 specifications, such as LGA 775 and Socket AM2 motherboards.

ATX 12v 2.0 specification power comparison table

+12v1+12v2+5v+3.3v actual power

8a 14a 18a 17a 250 w

8a 14a 20a 20a 300W

10a 15a 2 1a 22a 350W

14a 15a 28a 30a 400W

However, ATX specification does not stop at ATX 12V2.0 specification. With the launch of 65nm dual-core processor, the manufacturing process has successfully entered a new stage, which will become the main theme of this year. Intel developed a brand-new ATX 12V 2.2 PC power supply specification for its dual-core processor when the processor specification changed greatly.

ATX 12V 2.2 version

ATX 12V 2.2 belongs to the latest ATX power supply standard, and compared with ATX 12V2.0, the improvement is not great. It still follows the dual-channel 12V output design in the 2.0 specification, but it is modified and strengthened on the basis of the 2.0 specification. The most prominent are the following two improvements. ,

First of all, in order to provide powerful power for dual-core high-end platforms, it is impossible for Intel to add 450W output specifications to ATX 12V 2.2 specifications. This is due to the increasing power consumption of dual-core processors and the popularity of multi-graphics card technology and RAID technology. For high-end system platforms, high-power power supply has become an indispensable element!

On the load cross diagram above, we can see that the maximum combined output power of the dual-channel 12V power supply mentioned in the Intel specification reaches 450W, which can fully cope with the current high-end dual-core platform.

Secondly, in the new ATX 12V 2.2 specification, the conversion efficiency of power supply has a higher standard. At present, it is recommended (not mandatory) that the conversion efficiency of ATX 12V 2.2 is 80%. China is relatively backward, and the current CCC requirement is 65%.

Quasi-system power supply, ATX power supply alternative!

Quasi-system power supply still belongs to ATX power supply in principle, but due to the limitation of chassis space, quasi-system manufacturers have to transfer the operation object to power supply. Obviously, the huge ATX power supply can no longer be used, and quasi-system manufacturers must customize the power supply according to their own needs. Generally, the power supply is slimming by directly reducing the volume and space occupation. However, due to the different shapes of all kinds of quasi-systems, the layout of the internal space is also far from each other. Each quasi-system manufacturer must design independently according to its own situation, so as to make good use of the surrounding space and make the quasi-system light and compact.

So far, there is still no standard for quasi-system power supply. Of course, the problem brought by this particularity is also obvious, that is, the power of the quasi-system power supply is low, often only about 200-250 W, and the opportunity for users to upgrade the power supply is almost slim. Therefore, quasi-system manufacturers often customize the power supply according to AMD or Intel platforms to meet the power demand brought by users' upgrading or adding accessories to the greatest extent. The most common way is to strengthen the compensation output of a line.

Although the ATX specification specifies the output standard of each line. However, it is impossible for each output of ATX power supply to reach the nominal maximum output power at the same time. Due to the high power consumption of the current processor, Intel changed to+12V to supply power to the CPU, so the load at the+12V terminal is heavier, which will lead to the decrease of+12V. In the past, AMD's CPU usually took power from +5V, and the compensation circuit of the power supply automatically compensated +5V, resulting in an increase of+12V (now AMD's new generation CPU also takes power from+12V).

I believe that some friends who still use the previous power supply after upgrading the system will find that the power supply is incompatible with the new system. The main reason is that the early power supply has a strong carrying capacity of 5V, while the carrying capacity of 12V is relatively weak. Relatively speaking, high pressure is more dangerous than low pressure. At most, low voltage will cause the computer to work abnormally, while high voltage may burn out the hardware.

In view of the increasing demand for 5V and 12V load capacity in the system, how to realize the adjustment of these two voltage load changes without affecting each other? In order to ensure the stability of the output voltage, ATX power supply has designed a set of compensation circuit, which can automatically compensate according to the amplitude of the output voltage drop to offset the output voltage drop. But in general, ATX power supply will not provide a separate voltage stabilizing circuit for each output voltage, but compensate at the same time. For example, the output voltage of +5V in+12V and +5V in+12V starts to drop due to heavy load, and the power supply will increase the output voltage of these two circuits at the same time. If +5V is not controlled separately, the output voltage transition compensation will inevitably be+12V, which will exceed the rated voltage. This unique phenomenon is more obvious in the case of poor power design or insufficient output power!

In view of the above problems, at present, many quasi-system power supplies use magnetic amplification technology to improve the stability of power supply output voltage, and often separate 3.3V from 5V and 12V voltage stabilizing circuits-separate 5V voltage stabilizing circuits from 5V and 12V*** *, which means 5V and 12V can be adjusted independently. (Note: Even if three independent output modes are not adopted, a better power supply protects the outputs of +5V and+12V to some extent. When the voltage rises to a dangerous level, the power supply will turn off the output. The reasonable fluctuation range of positive voltage output by power supply is -5%-+5%, and the reasonable fluctuation range of negative voltage is-10%-+ 10%.

In addition, the power supply of quasi-system mostly omits the first EMI filter circuit, and the suppression ability of high-frequency interference at the input end and PWM itself is not as good as that of standard ATX power supply.

Of course, there are also some "small" manufacturers (such as Iwill and Haoxin) who simply follow the example of notebook computers and change the power supply to an external design. Only one input interface and necessary connecting lines are provided in the quasi-system host. Therefore, it should be difficult for you to have the illusion of upgrading this system!

Four. BTX power supply specification

The full name of BTX in English is "balanced technology extension", which means balanced technology extension in Chinese. This is a new motherboard architecture specification, which aims to establish a flexible general foundation with the help of standards used to build innovative desktop computer systems. The system needs the latest performance technology to meet the increasing requirements of users in terms of heat dissipation, energy consumption, structure, sound and electromagnetic compatibility. BTX specification provides developers with new tools and design space to support them to design desktop computer systems, whether small compact systems or large-scale scalable systems. Compared with the structural changes, the power supply of BTX has little change.

BTX power supply is compatible with ATX technology, and its working principle is basically the same as its internal structure. The output standard is the same as the current ATX 12V 2.0 specification, which uses a 24-pin connector.

BTX power supply mainly derives several power supply specifications from the original ATX specification: ATX 12V, CFX 12V and LFX 12V. Among them, ATX 12V is the existing specification, because the atx 12V 2.0 power supply can be directly used on the standard BTX chassis.