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Power good signal

The Power Good signal (power-good) is a signal provided by a computer power supply to indicate to the motherboard that all of the voltages are within specification and that the system may proceed to boot and operate.

ATX Power Good

The ATX specification defines the Power-Good signal as a +5-volt (V) signal generated in the power supply when it has passed its internal self-tests and the outputs have stabilized. This normally takes between 0.1 and 0.5 seconds after the power supply is switched on. The signal is then sent to the motherboard, where it is received by the processor timer chip that controls the reset line to the processor.

The ATX specification requires that the power-good signal ("PWR_OK") go high no sooner than 100 ms after the power rails have stabilized, and remain high for 16 ms after loss of AC power, and fall (to less than 0.4 V) at least 1 ms before the power rails fall out of specification (to 95% of their nominal value).

Cheaper and/or lower quality power supplies do not follow the ATX specification of a separate monitoring circuit; they instead wire the power good output to one of the 5 V lines. This means the processor will never reset given bad power unless the 5 V line drops low enough to turn off the trigger, which could be too low for proper operation.

Power Good values

Power good value is based on the delay in ms, that a power supply takes to become fully ready. Power good values are often considered abnormal if detected lower than 100 ms or higher than 500 ms.[1]

References

  1. ^ Manufacturer of a power supply tester

External links

  • ATX12V power supply design guide 2.01
  • Desktop Platform Form Factors Power Supply

power, good, signal, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, july, . This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Power good signal news newspapers books scholar JSTOR July 2016 Learn how and when to remove this template message The Power Good signal power good is a signal provided by a computer power supply to indicate to the motherboard that all of the voltages are within specification and that the system may proceed to boot and operate Contents 1 ATX Power Good 2 Power Good values 3 References 4 External linksATX Power Good EditThe ATX specification defines the Power Good signal as a 5 volt V signal generated in the power supply when it has passed its internal self tests and the outputs have stabilized This normally takes between 0 1 and 0 5 seconds after the power supply is switched on The signal is then sent to the motherboard where it is received by the processor timer chip that controls the reset line to the processor The ATX specification requires that the power good signal PWR OK go high no sooner than 100 ms after the power rails have stabilized and remain high for 16 ms after loss of AC power and fall to less than 0 4 V at least 1 ms before the power rails fall out of specification to 95 of their nominal value Cheaper and or lower quality power supplies do not follow the ATX specification of a separate monitoring circuit they instead wire the power good output to one of the 5 V lines This means the processor will never reset given bad power unless the 5 V line drops low enough to turn off the trigger which could be too low for proper operation Power Good values EditPower good value is based on the delay in ms that a power supply takes to become fully ready Power good values are often considered abnormal if detected lower than 100 ms or higher than 500 ms 1 References Edit Manufacturer of a power supply testerExternal links Edit Wayback Machine 31 01 2019 Power Good article on pcguide Wayback Machine 22 11 2009 ATX12V power supply design guide 2 01 ATX12V power supply design guide 2 01 Desktop Platform Form Factors Power Supply Retrieved from https en wikipedia org w index php title Power good signal amp oldid 1059648703, wikipedia, wiki, book, books, library,

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