ATX (Advanced Technology eXtended) is a motherboard configuration specification developed SFX; TFX; WTX; AMD GES; 5 EPS12V ATX also made the PS/2-style mini-DIN keyboard and mouse connectors Power Supply Design Guide, v · EPS12V Power Supply Design Guide v Insignia W ATX12V /EPS12V Power Supply: Designed to power select computers; W continuous power; ATX12V /EPS12V Specifications. We’ll answer PSU spec questions of modular vs. non-modular PSUs, EPS12V vv The EPS (Entry-level Power Supply) standard is.
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Modern personal computers universally use switched-mode power supplies. Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage. Most modern desktop personal computer power supplies conform to the ATX specificationwhich includes form factor and voltage tolerances.
ATX power supplies are turned on and off by a signal from the motherboard. They also provide a signal to the motherboard to indicate when the DC voltages are in spec, so that the computer is able to safely power up and boot. The desktop computer power supply changes alternating current from a wall socket to low-voltage direct current to operate the processor and peripheral devices.
Several direct-current voltages are required, and they must be regulated with some pes12v to provide stable operation of the computer. A power supply rail or voltage rail refers to a single voltage provided by a power supply unit PSU. First-generation microcomputer and home computer power supply units used a heavy step-down transformer and a linear power supply, as used, in for example, the Commodore PET introduced in The Apple IIalso introduced inwas noted for its switched-mode power supplywhich was lighter and smaller than an equivalent linear power supply would have been, and which had no cooling fan.
The switched-mode supply uses a ferrite-cored high frequency transformer and power transistors that switch thousands of times per second. By adjusting the switching time of the transistor, the output voltage can be closely controlled without dissipating energy as heat in a linear regulator.
Power supply unit (computer)
The development of 22 and high-voltage transistors at economical prices made it practical to introduce switch mode supplies, that had been used in aerospace, mainframes, minicomputers and color television, into desktop personal computers. The Apple II design by Atari engineer Rod Holt was awarded a patent,   and was in the vanguard of modern computer power supply design.
Now all modern computers use switched-mode power supplies, which are lighter, less costly, and more efficient than equivalent linear power supplies. Computer power supplies may have short circuit protection, overpower overload protection, over-voltage protection, under-voltage protection, over-current protection, and over-temperature protection.
The ATX standard followed specc manufacturers design [ citation needed ] to have power supplies also supply a standby voltage, so that most of the computer system could be powered off after preparing for hibernation or shutdown, spdc powered back on by an event. This standby voltage is generated by a smaller power supply inside the unit. The standby power source was a small linear power supply with conventional transformer, which was later changed to a switching power supply, sharing some components of the main unit due to cost- and energy-saving eps12g.
Power supplies designed for worldwide use were equipped with an input voltage selector switch that allowed the user to configure the unit for use on local power grid. Connecting the unit configured for the lower range to a higher-voltage grid usually resulted in an immediate permanent damage. When the power factor correction PFC was required, those filter capacitors were replaced with higher-capacity ones, together with a coil installed in series to delay the inrush current.
This is the simple design of a passive PFC. The first active PFC circuits just delayed the inrush. Newer PFC circuits also replace the NTC -based inrush current limiterwhich is an expensive part previously located next to the fuse.
An additional wire referred to as ‘Power Good’ is used to prevent digital circuitry operation during the initial milliseconds of power supply turn-on, where output voltages and currents are rising but not yet sufficient or stable for proper device operation. Once the output power is ready to use, the Power Good signal tells the digital circuitry that it can begin to operate.
In a common variant found in tower cases, the line-voltage switch was connected to the power supply with a short cable, allowing it to be mounted apart from the power supply. An early microcomputer power supply was either fully on or off, controlled by the mechanical line-voltage switch, and energy saving low-power idle modes were not a design consideration of early computer power supplies. These power supplies were generally not capable of power saving modes such as standby or “soft off”, or scheduled turn-on power controls.
Due to the always-on design, in the event of a short circuiteither a fuse would blow, or a switched-mode supply would repeatedly cut the power, wait a brief period of time, and attempt to restart. For some power supplies the repeated restarting is audible as a quiet rapid chirping or ticking emitted from the device.
When Intel developed the ATX standard power supply connector published inmicrochips operating on 3. Earlier computers requiring 3. The ATX connector provides multiple wires and power connections for the 3. In ATX-style systems, the front-panel power switch provides only a control signal to the power supply and does not switch the mains AC voltage.
This low-voltage control allows other hardware or software to turn the system on and off. As transistors become smaller on chips, it becomes preferable to operate them on lower supply voltages, and the lowest supply voltage is often desired by the densest chip, the central processing unit.
In order to supply large amounts of low-voltage power to the Pentium and subsequent microprocessors, a special power supply, the voltage regulator module began to be included on motherboards. Low-quality power supply manufacturers sometimes take advantage of this overspecification by assigning unrealistically high power supply ratings, knowing that very few customers fully understand power supply ratings.
Since certain variants, CPUs use lower operating voltages such as 3. Jumpers or dip switches set the output voltages to the installed CPU’ s specification. When newer CPUs required higher currents, switching mode voltage regulators like buck converters replaced linear regulators for efficiency. Rarely, a linear regulator generated these 3.
Later regulators managed all the 3. Cutting the pulse by the voltage regulator the rato of the 3. Some of these PSUs use two different chokes, feeding the to the 3. In designs using identical chokes, the pulse width manage the ratio.
Power supply unit (computer) – Wikipedia
Voltage drop on connectors forced the designers to place such buck converters next to the device. The latest specification is v2. The EPS standard provides a more powerful and stable environment for critical server-based systems and applications.
As power supply capacity increased, the ATX power supply standard was amended beginning with version 2. The requirement was later deleted from version 2. The rule was intended to set a safe limit on the current able to pass through any single output wire.
A sufficiently large current can cause serious damage in the event of a short spexor can melt the wire or its insulation in the case of a fault, or potentially start a fire or damage other components.
Each rail delivers up to a limited amount of current through one or more cables, and each rail is independently controlled by its own current sensor which shuts down the supply upon excess current. Unlike a fuse or circuit breakerthese limits reset as soon as the overload is removed. Obviously, if the group of wires is limited to 20A, so is each wire in it. The current limits for each group of cables is then documented so the user can avoid placing too many high-current loads in the same group.
Originally at the time of ATX 2. When the assignment of connectors to rails is done at manufacturing time it is not always possible to move a given load to a different rail or manage the allocation of current across devices.
In some cases, in violation of their own advertising claims to include it. The requirement was withdrawn as a result, however the issue left its mark on PSU designs, which can be categorized into single rail and multiple rail designs. Both may and often do contain current limiting controllers. As of ATX 2. A multiple rail design does the same, but limits the current supplied to each individual connector or group of connectorsand the limits it imposes are the manufacturer’s choice rather than set by the ATX standard.
The reasons given for this approach to power supply are that it eliminates cross-load problems, simplifies and reduces internal wiring that can affect airflow and cooling, reduces costs, increases power supply efficiency, and reduces noise by bringing the power supply fan speed under the control of the motherboard.
The overall power draw on a PSU is limited by the fact that all of the supply rails come through one transformer and any of its primary side circuitry, like switching components. This protects against system performance degradation, and against power supply overloading. Power supplies label their total power output, and label how this is determined by the electrical current limits for each of the voltages supplied.
Some power supplies have no-overload protection. The system power consumption is a sum of the power ratings for all of the components of the computer system that draw on the power supply.
The manufacturers of these computer system components, especially graphics cards, tend to over-rate their power requirements, to minimize support issues due to too low of a power supply.
Various initiatives exist to improve the efficiency of computer power supplies. Climate Savers Computing Initiative promotes energy saving and reduction of greenhouse gas emissions by encouraging development and use of more efficient power supplies.
Efficient power supplies also save money by wasting less power; as a result they use less electricity to power the same computer, and they emit less waste heat which results significant energy savings on central air conditioning in the summer.
The gains of using an efficient power supply are more substantial in computers that use a lot of power. Although a power supply with a larger than needed power rating will have an extra margin of safety against overloading, such a unit is often less efficient and wastes more electricity at lower loads than a more appropriately sized unit.
A power supply that is self-certified by its manufacturer may claim output ratings double or more than what is actually provided. Many power supplies create their 3.
ATX – Wikipedia
The two rails involved are labeled on the power supply with a combined current limit. For a description of the potential problem, a 3. In this case, loading the 3. The energy efficiency of a power supply drops significantly at low loads. Therefore, it epss12v important to match the capacity of a power supply to the power needs of the computer. Sepc curve varies from model to model examples of how this curve looks can be seen on test reports of energy efficient models found on the 80 PLUS website.
Most desktop personal computer power supplies are a square metal box, and have a large bundle of wires emerging from one end. Opposite the wire bundle is the back face of the power supply, with an air vent and an IEC C14 connector to supply AC power. A label on one side of the box lists technical information about the power supply, including safety certifications and maximum output power.
The CE mark is required for power supplies sold in Europe and India. Some power supplies come with sleeved cables, which besides being more aesthetically pleasing, also make wiring easier and have a less detrimental effect on airflow. A modular power supply provides a detachable cable system, offering the ability to remove unused connections at the expense of a small amount of extra electrical resistance introduced by the additional connector.
Many modular supplies have some permanent multi-wire cables with connectors at the ends, such as PC main and four-pin Molexthough newer supplies marketed as “Fully Modular” allow even these to be disconnected.
The long narrow profile of the power supply fits easily into low profile systems. The fan placement can be used to spdc exhaust air from the processor and core area of the motherboard, making possible smaller, more efficient systems using common industry components. External power supply could send data about itself power, current and voltage ratings to the computer. For example, genuine Dell power source uses 1-Wire protocol to send data by third wire to the laptop.
The laptop then refuse non-matching adapter. All other voltages are generated by voltage regulator modules on the motherboard.