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Pridružen/-a: Pet Nov 2004 23:38
Prispevkov: 177

PrispevekObjavljeno: Čet Dec 16, 2004 10:57 pm    Naslov sporočila: Napajalniki Odgovori s citatom

Tole sem objavil v enem drugem forumu, pa tukaj samo copy/paste, če komu prav pride:

No, tako... da se podobni dimni efekti ne bojo več ponavljali, je tukaj nekaj navodil:

1. če ne veš kaj delaš, najprej preberi kakšno navodilo.
2. Če se ne spomneš kako priključiti, če se spomniš, da si nekje nekaj zasledil, pa se ne spomneš kje... vprašaj strička googla z geslom npr. "PC power supply connector pinout" ali kaj podobnega.
3. Za vse ostalo je tukaj kratek povzetek:

poznamo v splošnem 3 oblike napajalnikov in sicer

LPX ("tastar", AT, PS2)


ATX ("tanov", ATX, ga najpogosteje srecamo)


SFX (IBMova pogruntavščina za razne miniaturne PCje)


Obstaja še NLX, ki je pomanjšan ATX. Potem pa so še razni specijalni napajalniki, npr. za strežnike ali posebne potrebe (npr. PC104, razni industrijski PCji in podobno), vendar kaj takega vam bo redkeje prišlo pod prste.

Obliki se tudi strokovno rece form factor.

Vsak PC napajalnik ima konektor za mamaplato (motherboard, maticno plosco...) in preiferne enote. Napajalnika oblike ATX in SFX imata ATX konektor, LPX pa ima AT konektor.

AT konektor zgleda tako:


Razpored prikljuckov je tak:
Koda:

Pin     Funtion         Wire color

1.      Power Good      Orange
2.      +5Vdc           Red
3.      +12Vdc          Yellow
4.      -12Vdc          Blue
5.      Ground          Black
6.      Ground          Black

7.      Ground          Black
8.      Ground          Black
9.      -5Vdc           White
10.     +5Vdc           Red
11.     +5Vdc           Red
12.     +5Vdc           Red


Upam, da je razumljivo kljub anglescini. Barve so samo informativne. Orientacija naj bo na 4 crne zice, ki so vedno skupaj na sredini in so GND - te so vedno crne.

Da tak napajalnik naceloma deluje, tak kot je, brez kaksnih prevezav. Edino kar sem opazil pri nekaterih, ki so mi prisli pod roke je to, da potrebuje neko breme na 5V. En upor 1k bo ze dovolj, da zazna da je "nekaj" prikljuceno. Na prikljucku 1 (oranzna) bo se po stabilizaciji napetosti pojavilo 5V, ki signalizira, da je z napajanjem vse OK. Pri nekaterih napajalnikih se tudi lahko zgodi, da je treba povezati pina "Power good" in +5V, vendar je to bolj vezano na maticne plosce. Glej spodaj razlago pojma Minimum Load Current.


ATX konektor pa takole:


Pinout za ta konektor pa je bolj jasen:


Pri tej vrsti napajalnika pa je potrebno sklenit pin PS_ON na GND (zeleno in crno).

ATX napajalniki imajo lahko se dodatno napajanje (za 3,3V, ce je poraba visja od 18A). Tak konektor pa zgleda tako (AUX supply):



Obstaja pa se 12V dodatni konektor:




Dodajam pa se razlago nekaterih pojmov okrog napajalnikov (copy/paste):


Mean Time Between Failures (MTBF) or Mean Time To Failure (MTTF). The (calculated) average interval, in hours, that the power supply is expected to operate before failing. Power supplies typically have MTBF ratings (such as 100,000 hours or more) that are clearly not the result of real-time empirical testing. In fact, manufacturers use published standards to calculate the results, based on the failure rates of the power supply's individual components. MTBF figures for power supplies often include the load to which the power supply was subjected (in the form of a percentage) and the temperature of the environment in which the tests were performed.


Input Range (or Operating Range). The range of voltages that the power supply is prepared to accept from the AC power source. For 110v AC current, an input range of 90v–135v is common; for 220v current, a 180v–270v range is typical.


Peak Inrush Current. The greatest amount of current drawn by the power supply at a given moment immediately after it is turned on, expressed in terms of amps at a particular voltage. The lower the current, the less thermal shock the system experiences.


Hold-Up Time. The amount of time (in milliseconds) that a power supply can maintain output within the specified voltage ranges after a loss of input power. This enables your PC to continue running without resetting or rebooting if a brief interruption in AC power occurs. Values of 15–30 milliseconds are common for today's power supplies, and the higher (longer), the better. The ATX12V specification calls for a minimum of 17ms hold-up time.


Transient Response. The amount of time (in microseconds) a power supply takes to bring its output back to the specified voltage ranges after a steep change in the output current. In other words, the amount of time it takes for the output power levels to stabilize after a device in the system starts or stops drawing power. Power supplies sample the current being used by the computer at regular intervals. When a device stops drawing power during one of these intervals (such as when a floppy drive stops spinning), the power supply might supply too high a voltage to the output for a brief time. This excess voltage is called overshoot, and the transient response is the time that it takes for the voltage to return to the specified level. This is seen as a spike in voltage by the system and can cause glitches and lockups. Once a major problem that came with switching power supplies, overshoot has been greatly reduced in recent years. Transient response values are sometimes expressed in time intervals, and at other times they are expressed in terms of a particular output change, such as "power output levels stay within regulation during output changes of up to 20 percent."


Overvoltage Protection. Defines the trip points for each output at which the power supply shuts down or squelches that output. Values can be expressed as a percentage (for example, 120% for +3.3 and +5v) or as raw voltages (for example, +4.6v for the +3.3v output and +7.0v for the +5v output).


Maximum Load Current. The largest amount of current (in amps) that safely can be delivered through a particular output. Values are expressed as individual amperages for each output voltage. With these figures, you can calculate not only the total amount of power the power supply can supply, but also how many devices using those various voltages it can support.


Minimum Load Current. The smallest amount of current (in amps) that must be drawn from a particular output for that output to function. If the current drawn from an output falls below the minimum, the power supply could be damaged or automatically shut down.


Load Regulation (or Voltage Load Regulation). When the current drawn from a particular output increases or decreases, the voltage changes slightly as well, usually increasing as the current rises. Load regulation is the change in the voltage for a particular output as it transitions from its minimum load to its maximum load (or vice versa). Values, expressed in terms of a +/– percentage, typically range from +/–1% to +/–5% for the +3.3, +5, and +12v outputs.


Line Regulation. The change in output voltage as the AC input voltage transitions from the lowest to the highest value of the input range. A power supply should be capable of handling any AC voltage in its input range with a change in its output of 1% or less.


Efficiency. The ratio of power input to power output, expressed in terms of a percentage. Values of 65%–85% are common for power supplies today. The remaining 15%–35% of the power input is converted to heat during the AC/DC conversion process. Although greater efficiency means less heat inside the computer (always a good thing) and lower electric bills, it should not be emphasized at the expense of precision, stability, and durability, as evidenced in the supply's load regulation and other parameters.


Ripple (or Ripple and Noise, or AC Ripple, or PARD [Periodic and Random Deviation]). The average voltage of all AC effects on the power supply outputs, typically measured in millivolts peak-to-peak or as a percentage of the nominal output voltage. The lower this figure is, the better. Higher-quality units normally are rated at 1% ripple (or less), which if expressed in volts would be 1% of the output. Consequently, for +5v that would be 0.05v or 50mv (millivolts). Ripple can be caused by internal switching transients, feed through of the rectified line frequency, and other random noise.
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