Introduction

There are now countless Web parts provider on the market. The opaque conditions by producers to the respective brands make it easier to get an overview. Today, we want to bring therefore some light in the darkness, and explain the current state of affairs. This includes in particular the current market situation. Also establishing explains short and thus understandable by PC power supplies on the following pages. Their transparency allows attention to some PR traps of the manufacturer and do not always everything what is specified. Because not everything on paper, can be applied exactly to reality.

Because again, power supply reviews are currently being planned, are also current technical issues such as the VRMs (voltage regulator module), addressed the power factor in power supplies or the LLC resonant converter. Who so every now and then would like to refresh his knowledge for the planned reviews, should have access to this report. The exact timetable of reviews not is clear yet which is why we hereby also a first response of the reader capture and explore the interest in this topic to.

In addition we show how manufacturers produce and work in their quality control provides an example. Not to forget is the important issue of power distribution, in particular the relationship between continuous and peak performance. We hope you enjoy the study of topics all readers!

Building a PC power supply unit

Part I

The PC or ATX power supply has the task of the AC voltage coming from the mains to convert in a less adequate for the system voltage. In fact it is a primary switch mode power supply. So a device whose switching – in form of power transistors – are controlled. They sit in the primary circuit, which is separated by the transformer from the secondary circuit. From 230 VAC (voltage alternating current = AC) electrical tension are + 12V (of derived)-12 V, + 5 V (of which derived + 3.3 V) and generates a separate. An own transfer is available for the latter (see small transformer). So, one could speak that there’s basically two power supplies are integrated, one for the main supply, one for standby.

Now the process of care imagine so, that the PC at the turning on of the separate + 5 VSB is supplied. Internally, the switches for the corresponding rail be opened. Basic parts of motherboards such as the control logic or the clock are by now. Before the PC however comes up, whether the tension can be maintained with otherwise no issues checks for security reasons. If all goes well, a signal is output, which is known as “Power Good”. This conveys that everything is and the boot process can begin.

The sign of the start is processed internally, so the switch of the Standbyschiene are closed. For this the way to the main transformer, which produces other tensions that are relevant for the normal operation opens now. The PC is powered now at all levels and can pursue its task panes.

Part II

We have already covered, what is the main task of the PC power supply, and how the operation with the Standbyschiene and main supply works. Now we are dealing with the surrounding structure and electronics. Initially the network filtering.

As many already know, the power supply via the cold device cable power is connected. These houses include phase and neutral for a closed circuit. A separate ground is in the process. The longer connection in the plug head, this is installed as first or pulled out automatically as the last. This is also important because it security serves and derives for people harmful tensions over the Earth. A contact must be always made. The energy in the PC, neutral flows over the stage manager or return conductors lead, however, back the return to the actual source (the generator of electricity utility).

Now the following problem arises: one can assume that not only useful energy is fed via a line, but also electrical disturbances can enter in the power supply. As well, it distorted the image of voltage in the opposite direction. Order this issue contrary to to work, always a line filter is upstream the actual power supply. The bottom visible image shows first filtering measures by two blue Y capacitors and a green X-capacitor.

Generally, a source can emit electromagnetic interference that comes via a coupling path to the victim, the so called interference sink. Through the use of capacitors with complementary chokes, attenuation are made on both sides. Depending on the scope, you can already distinguish between good and moderately developed filtering. Also internal sources of interference must be counteracted be and appropriate shielding prevents EMC complications.

In due course place the subject in the coming tests is revisited and explained on the basis of the specific noise components. For current track, it is enough to know that there are such errors in both directions, which must prevent a quality power supply.

Part III

So far, we have spoke about the line filter, which is located in the DC area. It now follows the previous power factor controller operated for the first time with DC. To different rectifier bridges (see picture) or diodes transform according to power the electric voltage.

There are distortions, which are the voltage and the current not more synchronized to each other by a non-linear absorption of the components. One speaks of a shift, which must be limited according to law from 75 watt output. On the one hand, because these errors cause complications for the electricity company, to another the so-called reactive power is the shift between the two sizes. Within the apparent power, a distinction is made between active and reactive power. On itself can not be used latter energy and it is made also into heat, so you can capture difficult it. However, in principle exists and represents a burden for the components.

Therefore the just mentioned before power factor controller is used. With passive or Active PFC (power factor correction = power factor correction) the phase shift is corrected with a value of 1.0 reflects any differences and a value of 0.0 means the maximum phase shift of 90 ° and thus the highest share of power. That there are different designs within the active correction, is first of all irrelevant. What is interesting for us is that the active process is controlled by an IC (integrated circuit) and thus more complicated as also more effectively fails. A power factor up to 0.99 is achieved. The passive version consists of a simple choke and thus cheaper, but less effective. On the image of the primary field below is to see where the PFC is carried out.

After the screening by a capacitor, the current is fed through the aforementioned switch the transformer. This generates the respective electrical voltages of the individual windings. Basically, it consists of two coils, which are facing. The paradox is now switched back from DC. Namely a higher frequency, with rectangular voltage of the transformer works.

After the transfer by the transformer, the tension is now final rectified on semiconductor diodes. What applies to the line filter, can be applied also output side. The voltage is stabilized it and so that no harmful frequency shares or AC parts reach the PC, an additional filtering effect. That is the quality of the power supply necessary, because the operations in the power supply definitely cause such problems, and the tension is as clean, defined according to. While some readers are likely to already of ripple & noise have heard, to German ripple. This describes not completely smooth AC shares. The last filter and stabilisation measures be taken in the shown here are secondary.

Often, users wonder whether the PC power supply 500 watt also 500 watts on the net takes performance, even if the PC requires only 250 Watts. This is not because a Digital PWM chip strives to control that only the desired amount including the occurring loss performance goes the semiconductors by its clock signal. Apart from the efficiency is exactly so much recorded as is released. An intelligent solution, that would otherwise cause thermal problems in giving.

Current technologies

12 Volt distribution

The + 12 V rail is without a doubt the most claimed, they must provide 90% of the energy of a PC. The + 3, 3-V- and + 5 V rail play so an increasingly small role in the RAID system, for example, never all disks at the same time fully charged, but use of CPU and GPU not rarely parallel under full load. Today’s manufacturers of high-end power supplies often advertise to have devices available that are equipped with three or even more 12 V Rails. We will clarify what thus has it on himself, in the following section.

A power supply can always only a certain + 12-V performance, the combined power (overall performance), provide. Let us take as an example, that there are maximum 30 A. Now however, is on the packaging, that rail rail and 12 v1 20 A 12 v2 has also 20 A.Are but 40 A?Specifying only shows how much ampere maximum can be taken of the overall performance (30 A) onto a rail. High load of 12 v1 there, for example, all 20 A, can be made available, and consequently there are only 10 A possible on 12 v2. Just as it may 15 A + 15 A, 18 A + 12 A and so on be. You should look always at the important combined-power indication when you buy a power pack so. It is problematic if multiple components at one + 12 V rail sit and (based on our example) consume more than 20 A. In this case, the power supply is then overloaded. A single + 12 V rail therefore has the advantage that she rarely too much will be charged, because it is always the full capacity of the power supply available.

The tracks are logically and often also called “Virtual Rails”, because they run on a common transformer, are not really separate only sharing a strong + 12-V supply represent. You be secured locally in the case of an overcurrent protection (OCP), which defines the cut-off point of the power supply. Single-rail power supplies with a single + you can’t 12-V rail, however, or only critically by OCP hedge, because the performance of a single-rail is so high, that there are dangerous currents already before of the OCP point (which must logically be rail on the maximum power). OCP is almost meaningless in this case. In the short-circuit can occur easily when single-rail concepts to corruption of PC components. Same problem applies also for multi-rail supplies with very strong 12 V Rails. Thanks to this risk potential, Intel suggests a limit of maximum 20 A per track in the ATX policy.

DC-DC technology

Usually the + 3, 3V be-, + 5 V- and + 12 V voltage from a source transformer generates. + 3.3 V is derived most of + 5 V and is its dependent. The transformer emits only the 12-V voltage at power supplies with DC-DC technology. Thus he must convert only once together with the fact of AC to DC, that the now strong pressure + 12-V voltage facilitates the overcoming of resistances, significant benefits in efficiency means. The + 3, 3-V- and + 5 V voltage are by power from the + 12-V rail is derived. This is done for reasons of space often on an additional Board, which houses mainly fixed material capacitors, chokes, Controllchip and transistors.

Another advantage of DC-DC technology is the stability improved (in good implementation). Is for traditional power supplies to correct a tension in the transformer increased or reduced, the other voltages are directly affected and be changed incorrectly as well. Because the lines in DC-DC power supplies independent filter, this problem can be avoided by a separate regulation. Finally more importance in the new technology on the 12-V line, and therefore higher performance volumes is the power-hungry PC components on this all-important line available. Since hardly needed the smaller tracks at today’s hardware, this is clearly a real step into the future. This topology can be improve if it not too much burdened small pipes due to their dimensioning the efficiency on the DC side compared to traditional methods. Thus, typically 80Plus-Silber-Niveau can be reached.

LLC resonant converter

Many current high end power supplies use a LLC resonant converter to reduce the switching losses to the transistors and thus to increase the efficiency. This includes a small explanation: when an open switch, a high current flows, but it is up to almost no voltage. Exactly the reverse is closed the case: a high voltage is present, however, almost no current flows. Between the opening and closing a delay arises (the switching process takes time), in which both voltage and current concerns. Multiplying these two devices, you get the power loss through the switching delay:

The LLC resonant converter now allows that one does not then turn must, when still a high voltage, but only when the voltage undergoes its zero (zero voltage switching). As a result a lot of power dissipation can be saved.

Other

Japanese capacitors

No letter has so influenced the marketing culture in power supplies, such as the C in the schematic. There is talk of the capacitor that stores energy in an electric field and – as mentioned – can smooth the output voltage. Now many manufacturers, are advertising that they on Japanese 105-° C-set models. A temperature resistance up to 105 ° C is to be ensured for good models and each purchaser can detect that conventional 85 ° C are lower and therefore bad.

However, the reader is thus led up the garden path, because to the temperature indication always the time must be taken into account. It is therefore in principle not wrong that a 105-° C-capacitor is better, but only if a duration allows the comparability. The component goes while not actually destroy even after specifying such as 2000 hours. Much more limited specified that that the capacity is then decreasing by 20%. In addition, it should be remembered that, in the PFC section by the relatively small currents, hardly losses occur and mean a thermally perfect job for the condenser. At least in the case of Active PFC the screen member is relieved and you can choose him easier, smaller and cheaper. 105 ° C there usually never be achieved. Such information also apply to boards or semiconductor, which only show under high conditions head of rail damage or dysfunction.

Japanese models have their PR popularity therefore, that she have a good electrolyte formula (= electrolyte cathode of Elektrolytkondensators) use and are well sealed, making the liquid material to the slides so quickly can escape and the capacitor is generally less sensitive. This is embezzled that an expensive Taiwanese model with a cheap Japanese make quite able to keep up. Just because a member from Japan comes, we must fasten the “grade” also on different quality classes not only on the basis of the origin. Our picture shows a typical 105-° C-condenser of Nippon Chemicon from Japan.

Such as vitamin C for colds, a quality condenser helps the sales figures of the manufacturer. Vitamins are healthy, which is well known, one can also exaggerate it. Until a capacitor is broken, the fan by the mechanical movement is worn several times. In addition is often argued that a Japanese model affects the power quality. Parameters play a role which have to do nothing in principle once in the formula, but in the ripple and noise, for example. Much more is the capacity depending on current load and frequency significantly, to obtain a clean image. Some manufacturers use the positive effect in fresh and visible solder a model on a line fall. Of course, the voltage image is improved by the additional capacity, it doesn’t but does not matter whether you install it internally or externally, where one uses it for PR purposes.

In the closely-populated secondary circuit, the device still has meaning. Whether a Japanese model so now is a miracle or pointless can be referred to as everyone for itself must decide. In any case, we believe the truth lies somewhere in between.

Cooling concepts

A familiar methodology, are passive heat sink as well as the ventilation by a fan to cool the PC power supply – where is the latter measure directly related to the effective flow of air. In the field of PC power is important. She must provide not only the system with the required amount of energy, but is also part of the concept of cooling in the housing in the case of the ATX specification. In the development you will need to cover forced not only to the electronic, but also with the physical arrangement. Even when power supplies are now often below placed and therefore decoupled, they wear at least above off parts of the waste heat from the CPU and motherboard. Therefore we now slightly more attention this important topic, by common cooling concepts in power supplies, we show.

In the purely passive concept the heatsink fall in bulky, they must compensate for the removal of heat by the air movement almost entirely. Nevertheless the temperatures are very often higher than models cooled with active and the market is so small that so far mainly smaller models are represented up to 450 Watts. Everything else is physically still difficult to realize. In addition to the sprawling heatsinks, great importance to come should above all the components. These are often up to 50 ° C, so easily operate with these temperatures.

The active concept, a fan can either top-down cover the entire board space, or it is placed horizontally to the Board. In the latter case it must access rule due to the low overall height 80 mm fan. Not all components are included so the airflow and not seldom very loud, the fan turns with high exerting minimum. However making an adequate cooling topology in tunnel form, so the heat sink take off again much of cooling and heat is fed into the tunnel. In this combination, the 80-mm approach can achieve its best performance and other ideas exceed cooling technology.

Because of the wide area 120 and 140 mm fan is the vertical cooling often quieter regulated, except that the heat sink here not too bulky may be the lower regions on the circuit board from the top down or need to be achieved. If necessary, miniature may be so in the wake of larger pieces.

Often, the fans will load as also temperature-controlled. To avoid high temperatures, the fan turns on gradually depending on the load, heat production increasing but still strong, ensures a faster increase in the temperature control. Semi passive models it mixes a not up in critical areas, before the rising temperature compensated for the fan. This affects particularly positive effect on the noise, but less well on the lifetime of the components. In the case of low-loss circuits, this should make now however hardly problems.

Network production

An example from Enermax, we indicate how and where a manufacturer of power supplies manufactures. Still, let’s take a quick look at the quality control. As a producer, Enermax has its own factory in Guangzhou, China. A complete monitoring of the production process can be better implemented as a contract with manufacturers (OEM) and the conception of different topologies is through its own R & D department at Headquarters. Most manufacturers have around Shenzhen (Guangdong Province) their factories, with a few exceptions such as SuperFlower or Impervio (about IS Quasar), which produce in Taiwan. External suppliers carry now various components such as controllers or the capacitors to these locations, where they are assembled and processed. So, most of the components are bought while some manufacturers such as CWT save money where they build the pipes themselves. In the factory runs so everything together and must be logistically coordinated.

As with most manufacturers usual, running many sections, such as the cast of the component or solder, full production off automatically, with some handles or final checks just yet of people are made. Usually sits down much of the work force of migrant, seasonal changing their jobs and therefore new employees must be trained. Of course such a factory but also has high professional staff and a corresponding management in factory management.

Here we see a control of manufactured Revolution85 +-power supply, in particular the final inspection is carried out by temporary workers. The visible FAST test station may not the latest or most expensive, is the basic function check – up on the case full – power supply however totally sufficient. Usually the quality is checked after each step and each new design must be tested in the hard test course previously.

The latter test series are often held at Headquarters, more specifically in the Development Department. This also tests under real conditions are in addition to the most modern test stations of chroma used. Current platforms and graphics cards running for days with system power supplies, to ensure the long-term compatibility and stability. Away from Tinker’s engineers on new ideas. Otherwise, the building houses the Executive level and the global management and various offices for the daily business. At the entrance, visitors can admire older as newer hardware.

Market situation

As mentioned in the introduction, there are a variety of brands, with numerous vendors sometimes have same contract manufacturers. That is, there are different manufacturers on the German market of less than there are brands and series. You should but don’t be fooled, because the same producer does not mean that the models of the provider are always identical. Each producer has several power supply designs, which arbitrarily to configure and modify.

However, it is interesting to note what producer who manufactures. To do this, you, can use some indicators without having to open the power supply. A UL certification number such as such as E161451, is located on the side label with the manufacturer’s instructions. Enter it on the database website, one can identify the actual producer under “UL File Number”. Should be handled gently but with the result, because some providers despite external production – have assigned their own numbers such as Zalman or Antec.

The best known producers include Enermax, SEASONIC, FSP, channel well technology and enhance. These can be identified from the outside on the basis of the input filtering, which is often similar. If you aufschraubt the power supply, the form of the heat sink, tags, or Trafobeschriftungen are crucial for the identification.

In this situation, the customer has an edge, he should use. The wide selection in the middle class, he can quickly find alternatives and is dominant in the relationship to the seller. We speak with this extreme of the buyer’s market. The other advantage commutes one automatically, because prices fall by strong competition and new series reduce the cost of the old. Price the customer so feel compelled to nothing, unless it can be 80Plus guided by certificates, because you get at low prices of course not always the desired efficiency or other features, such as cable management. Also, an interesting effect is that many manufacturers in the guarantee set if preceded by another. At this point, we would point out however that a bare year says no statement about the quality and courtesy of support services. As a reader, one should also not underestimate its influence and play this fact situation.