Intel ATX 3.0, Design Manual

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Electrical
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Parameter Minimum Maximum
V
IH
open circuit - -5.25 V
Ripple / Noise 400 mV p-p
NOTES:
1. Negative current indicates that the current is flowing from the power supply to the
motherboard.
2. Due to PS_ON# toggle on/off frequently, system and PSU component’s reliability should
be considered based on the days, months, or years of claimed warranty listed on product
specification. Refer to Document #575961 PSU design consideration for S0ix mode.
Figure 4-4: PS_ON# Signal Characteristics
4.3.4 +5VSB – REQUIRED
+5VSB is a standby supply output that is active whenever the AC power is present.
This output provides a power source for circuits that must remain operational when
the five main DC output rails are in a disabled state. Example uses include soft power
control, Wake on LAN, wake-on-modem, intrusion detection, Alternative Low Power
Modes (ALPM) or suspend state activities.
The power supply must be able to provide the required power during a “wake up”
event. If an external USB device generates the event, there may be peak currents as
high as 3.5 A, lasting no more than 500ms.
Over current protection is required on the +5VSB output regardless of the output
current rating. This ensures the power supply will not be damaged if external circuits
draw more current than the supply can provide.
With new modes of operation for computers like Alternative Low Power Modes (ALPM)
the continuous current rating of the 5VSB rail is recommended to be at least 3 A.