Intel ATX 3.0, Design Manual

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Reliability
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10 Reliability
10.1 Reliability - RECOMMENDED
The de-rating process promotes quality and high reliability. All electronic components
should be designed with conservative device de-ratings for use in commercial and
industrial environments.
Electrolytic capacitor and fan lifetime and reliability should be considered in the design
as well.
10.2 Reliability – PS_ON# toggle for S0ix mode -
REQUIRED
In order to optimize desktop platform power consumption, Intel provides design
recommendation to enable PSU PS_ON# toggle on/off during S0 idle power mode
(S0ix) to save both system and PSU power. The PSU PS_ON# may toggle on/off every
180s (PSU to be on for 1s and off for 180s) when customer desktop designs
implement S0 idle which is different from the legacy desktop platform design that
PS_ON# only toggle once when turn on. The S0ix mode is used in systems that use
Alternative Low Power Modes.
If the computer turns on/off every 180 seconds the worse case scenario would be 480
times in one day and 175,200 times in one year. The power supply needs to be able
to handle these many cycles for the life of the power supply.
To have better user’s experience and avoid PSU fan acoustic noise annoyance, system
and PSU designers shall have at least two seconds delay time for the PSU fan to spin
up after PS_ON# assertion. PSU is expected to support running at full load without
any electrical, thermal components (i.e., IC, MOSFET, diode, transformer, inductor,
capacitor, relay, fan, etc.) damaged or degradations during the period of time before
the warranty expired. Due to the frequent PS_ON# toggle on/off, system and PSU
component’s reliability should be considered based on the days, months, or years of
claimed warranty listed on product specification. This is also mentioned in Section
5.3.2 .
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