When faced with the question of what a power supply is, I’m sure the vast majority of you will say that it is to this component that current is connected and which is responsible for providing power to everything. the rest, and indeed you are right although a little basic level. For this reason, we are going to go into detail to tell you in depth not only what it is, but how this vital component works.
What is a diet and how does it work
As we have already mentioned, the source is the one that is responsible for providing power to the rest of the PC components. But, first of all, you must understand that there is a vital difference in terms of power supply and that it could not be realized if the source does not do its job, and the energy that comes to us from the electrical outlet of the outlet is alternating current. And yet, PC parts operate on direct current. Therefore, one of the subcomponents that make up the power supply is the AC / DC converter (yes, like the heavy metal strip), which literally converts AC to DC current so that the PC can use it.
But the thing doesn’t end there; In addition to converting alternating current to direct current, the source must be able to supply the PC components with the exact voltage they need, and as many of you know there are mainly three values needed: + 12V, + 5V and + 3.3V. Therefore, internally the power supplies also have voltage converters to be able to give each component exactly the voltage it needs, no more and no less.
In addition to this, all power supplies have filters (these are the Y and X capacitors that can be found both in the input socket and in different components) which are responsible for ensuring that current is supplied without electrical noise, which we generally call “clean flow”. The quality of these filters depends on the fluctuation of the current supplied, and they bear a large part of the responsibility in terms of efficiency and protection systems.
How does the power supply work?
As we have already mentioned, the first function of the power supply is to convert alternating current to direct current, and this is done with the AC / DC converter. In the past, this same converter had three outputs (for voltages of 12, 5 and 3.3 volts) but it was quite inefficient and also generated a lot of heat, so modern sources convert all the voltage between them into + 12VDC, and then through three DC / DC converters Voltages generated independently of +12, +5 and + 3.3V. This is done because the less used voltages (5 and 3.3) are not converted if they are not used, which saves a lot of energy and heat.
Once we have the voltage we need, it is filtered using inductors and capacitors, and two more parameters come into play here: the voltage regulation to ensure that the voltage is stable and the electrical noisebecause the louder the noise, the more the components wear out from the heat. We will explain this.
PC power supplies use switching technology to convert alternating current to direct current; When the rectifier is turned on or off, pulses of direct current are generated at a speed established by the input of alternating current (which in the case of Europe is 50 Hz, but in Mexico, for example, of 60 Hz). These pulses generate noise.
The current of each voltage passes through a inductor (called chokes) which stabilize and smooth the wave frequency of these pulses, thus reducing noise. Then it goes to the condensers (the famous japanese capacitors come into play here), which store electrical charge and release it without the noise we talked about. The way to do this is that if the voltage entering the capacitor increases or decreases the switching frequency, the charge of the capacitor decreases or increases but in a much slower manner than the switching frequency, while the output of the capacitor is always fixed, without variations, or as we have already said, “clean”.
Obviously, it is almost impossible to get a perfectly smooth graph in terms of the output voltage, because even though we have eliminated almost all the noise, waves (ripple), small peaks and dips in the output voltage. are created. This is where the large capacitors arranged in series come into play again, because the slower the change between the higher voltage and the lower voltage, the more stable the output voltage.
Some of you may be wondering why a lot more capacitors are not being inserted at this time, and the answer is that it would reduce the efficiency. No electronic component is 100% efficient and a small part of the energy is always transformed into heat. In the case of condensers, almost all of the heat they generate is precisely due to the electrical noise they remove, but yet this is the reason why we will normally see that sources have two of those famous big capacitors and nothing else. more. We have to find a balance.
Let’s take an example: in the following image, you can see the Ripple from a source that doesn’t have good filtering, or in other words, its capacitors are not of good quality.
Now in this other picture you can see the + 12V output of a high quality power supply.
After all of these leaks, there is still a lot of work to do before cutting power to the rest of the PC components. As we mentioned before, the voltage regulator has a very important responsibility as it is the voltage regulator who is responsible for determining how well the source responds to sudden changes in load (or consumption), like when we start a benchmark. .
This is where Ohm’s famous law comes into play, which defines that the more the intensity of the current (Amps) increases, the more the resistance increases, and the more the resistance increases, the more the voltage rises (the resistance is the only value which remains unchanged since it depends on the physical components). A good quality source should be able to compensate for all of this, usually through internal monitoring performed by the ‘supervisor IC’, able to indicate to the source’s PWM controller that the rectifier should switch to a different frequency to adjust the voltage. . Release.
In this regard, digital power supplies are significantly more efficient than normal power supplies, as the monitoring is done digitally, which significantly speeds up the compensation. The slower this switching, the more the components suffer from thermal wear, which also reduces efficiency.
In addition to everything that we have explained so far, we must keep in mind that in reality the PC works not only with three voltage values (12, 5 and 3.3 V), but for example the DDR4 RAM uses between 1.2 and 1.35 V to operate. The voltage regulator is also responsible for this, providing the voltage that each component needs; for example, in the case of RAM, the voltage is supplied by the + 3.3V rail, since it is the closest.
Types and categories
Power supplies can be categorized by tier, but this is an assessment of how well they function, which is subjective after all. However, they can be categorized starting with their effectiveness as determined by the 80 Plus certification.
The EEC (European Economic Community) has established that the parameters defined by the 80 Plus Bronze certification (whether or not they have this certification) are the minimum for a manufacturer to sell its products in Europe. In any case, this certification is already held only by entry-level power supplies, while the Silver and Gold seals are much more common, and the Platinum and Titanium are already reserved for high-end power supplies.
On the other hand, we can also classify a food by its size or its form factor, since it is defined by a standard:
- ATX: the current standard, with dimensions of 150 x 150 x 86 mm, although these are also ATX sources which have a greater length as long as the height of 86 mm and the width of 150 mm are respected.
- SFX– Dimensions are smaller because they are designed for small form factor systems. They measure 100 x 125 x 63.5mm and require an adapter to be able to fit them into standard ATX cases.
- SFX-L: is a variant of SFX sources that allows you to install a larger fan. They measure 130 x 125 x 63.5 mm.
- TFX: they have dimensions of 85 x 65 x 185 mm, and are generally intended for special equipment and servers.
- Flex ATX: this is a variant also used in servers and special equipment which has the particularity of allowing hot plug and play, that is to say that in systems with two redundant sources, the one can be removed and the other installed without shutting down the system. They measure 150 x 81.5 x 40.5 mm.
